I just did a London Paris trip in September. I was celebrating my 50th birthday and due to circumstance I ended up doing this solo. Late September was great. Fringe of the Peak seasons, shorts or jeans with tshirts, I only got rain full on one day (France) and one day there were some sprinkles but nothing heavy or long.
I did Sunday thru Thursday in London (Five full days), caught the Eurostar to Paris Friday at the crack of Dawn and stayed in Paris (with Saturday being spent at DLP) till Sunday late afternoon and then returned to London Sunday night and flew home to the US on Monday Morning.
I'll tell you right now there's no way I would have gone to France UNLESS I was doing Disney. It's RIGHT THERE, and I knew I'd never plan a trip to France again so I was doing Disney. HaHa.
I planned it all myself and except for one day tour I used public transportation for everything.
I flew out Saturday afternoon (Premium Economy is worth the money if you can swing it) and arrived in London Sunday Morning at 9am. I purposely chose my hotel to be at a transportation hub (King's Cross/St Pancres). I pre-bought my Oyster Card (transportation pass) and loaded it with $35 dollars. It was sent to the US. You can buy a card on site at the airport, I just chose to pay a small fee to have it sent ahead of time and to get a tourist card.
Oyster Cards are good on The Tube, Trains (in the London and outlying areas only), buses, and River Buses (boats). Because it's preloaded it just subtracted fares until you reached the cap of a one day use ticket and then the rest of the day was free (boats do not go towards that total they are stand alone). When your card gets low you could refill it at the station using a machine (swipe pass, swipe CC, pick reload amount, and Done).
I took a direct tube line from Heathrow to King's Cross (home of Platform 9 3/4) with my luggage. No problem. I choose a hotel right next to the station and walked out and to my hotel and checked in (room was ready yea!). King's Cross has multiple tube lines and trains so I wanted it as I could get to anywhere in Central London or adjacent with no/one transfer from either a bus, a tube or a train.
I spent Sunday at the British Library (a 5 minute walk from my hotel) and then doing a bit of supply shopping at Tesco Metro (sort of like a
Walmart Neighborhood Market) and just some walking around and taking in the sights.
I traveled by tube to:
Buckingham Palace
Westminster Abbey
Parliament/BigBen
London Eye
Tower of London
Oxford Street
Southbank
Thames River ( I had an afternoon Tea Cruise on the Thames)
I traveled by bus to:
British Museum (there are tubes but the bus actually had a stop right across from the Museum)
I took an Overland Train to:
Hampton Court Palace
All of these including my tube trip to and from Heathrow Airport were paid with my preloaded Oyster Card. I believe I added an additional $20 and came home with maybe about $10 on my card. (the airport desk could not refund my money as I needed to send the card back for that but I wanted to keep my card so I just considered it a cute souvenir (it actually is a keepsake designed card so not like the utilitarian ones you buy at the stations)
I took one day guided tour that had a pickup from a hotel about a 5 minute walk from my hotel to:
Windsor Castle
Bath
Stonehenge
I actually did not do any sit down resturants. I was on the go and had quick grab and go breakfasts, ate lunch at take away counters while sightseeing, and at night would do just light easy to pick up food either from the markets (M&S, Tesco, or the Farmers Market by my station).
Eurostar to Paris:
This was a separate ticket, buy early it's cheaper and they actually do run out of seats. I upgraded and it was totally worth it. I did not buy a transport card for Paris as I didn't actually take enough rides to equal the lowest priced mulitfare offer. I did use one taxi in Paris as it was easier than public transportation.
St Pancres Station is the Eurostar Station, I took it to Gard Du Nord. I had brought both a large and small suitcase. I actually checked my large bag into King's Cross' Left Luggage service and only traveled with my carry on, it was very convenient. Again I chose a hotel that was a 3 minute walk from the station. From there I could catch a bus, a train, or a Metro (underground). I was actually not all that interested in Paris as a destination but as I did want to go to DLP I decided to have a day in Paris. I went to the Eiffel Tower, walked along the Seine and then spent time at The Louvre. Saw a few things from transportation but really these were the two places I wanted to see. I had dinner that night at a street café (which is just an iconic meal that I recommend you do, it was great).
Saturday Morning I got up and caught an early train to DLP. (it is a short trip, little less than an hour) It's a one transfer route from Gard du Nord. You buy the tickets at the booth, I suggest buying both at once as the line to get a return to the city ticket at the DLP station was huge and I had been warned it would be. There are trains from London to DLP so you could go there first (I believe there is one transfer) and then base out of that area and catch the train into Paris Proper to sightsee.
I returned to Paris Saturday night. I had planned to go to Notre Dame Sunday morning before returning to London, but it was the one day of my trip that rained. Instead I opened up my French doors and slept in/watched tv/listened to the rain. I got up and got a leisurely late lunch at a local shop then got on the Eurostar back to London.
After 8 days I was busted out tired. I retrieved my luggage and just decided to go to my last hotel. I chose to splurge my last night and stayed at the Sofitel at Heathrow which connects via a walkway to Terminal 5 (international). I had dinner there, repacked all my bags and then got up Monday and flew home.
It was great! I did not regret planning my own trip and doing things in my own time. I really liked my itinerary better than the package tours I reviewed and honestly I didn't feel like an agent could have gotten me any better prices. In fact I did pay less for my trip than a friend who went a few months before me, but she was doing packages for the sake of Wimbledon and different times of the year of course. But I actually had a lot more freedom and saw much more.
I know this is long and crazy but I just wanted you to see that a self planned trip is doable.
I did upgrade transportation (both BA flights and Eurostar) and I'd do it again in a heartbeat. Extra leg room, free drinks, free luggage, less crowded, more attention.
I got a CC that had no travel fees through my bank and used it almost exclusively (I did have a couple hundred Pounds and couple hundred Euros for incidentals). It was great as I had the money for the trip in a savings account at the same bank and would go in and pay off the card every other day or so (after checking it online) so that I could manage my budget and keep track of purchases and rule out any fraudulent charges.
I enjoyed doing things at my own pace and picking and choosing what I 'visited' and what I toured more in-depth.
The London Transportation System was very easy and honestly much more user friendly than the Paris Transportation.
Even having only half remembered High School French (as in maybe 6 common phrases and only basic vocabulary) Paris was very easy to communicate in most tourist venues.
Both countries were super friendly and very forgiving of the American Tourist who sometimes forgot words or needed a little guidance.
Please feel free to ask my any questions. I had such a good time and hope that you do as well.