Tracey
Is there any chance that you could move your DLP trip to August? The reason I suggest this is that the park's summer opening hours (9am to 11pm) come to and end on 1 September. We've always found that the extended opening hours make for a much more enjoyable stay - the first few hours are great for riding all the main attractions, then we take it easy around the park and pop back to our hotel for a mid-afternoon swim, and still have the evening to enjoy in the park. This strategy avoids the worst of the queues, gives us plenty of time to relax and we enjoy the park at its best time (after dark). From 2 September park opening hours will be 10am to 8pm on weekdays, and 9am to 8pm weekends.
A good unofficial website, including hotel prices can be found at
http://www.dlp-guidebook.de/index_e.htm
Are you planning to stay on-site? If you are, I've found that the official UK DLP brochure is the most competitive, although sometimes Bridge Travel have slightly cheaper prices. Staying off-site can be much cheaper, but relies on either having a car or staying at hotels which are near railway stations (the easiest way to get to DLP is on the RER railway, which is a local commuter line). Unfortunately no hotels run free shuttles to the parks as there is not enough demand for this service. All in all staying on-site is by far the most convenient, but you do have to pay Disney prices for the hotels. My favourite is the Sequoia Lodge - this is the cheapest hotel with a swimming pool. If you don't think that you will use the pool, I would recommend the Cheyenne Hotel. It has a fun Wild West theme, and the rooms contain a double bed and bunk beds which might be useful if you have children who don't want to share a bed.
In terms of getting to DLP, I would
STRONGLY recomend that you go by Eurostar is you possibly can. It is a wonderful service, and beats flying hands-down. Even if it costs slightly more than flying I'm sure that you won't regret paying for it. The transfer from the airport to the parks is quite a frustrating experience (ask Bev), while the train takes you literally to the gates of the park. If you can get to London in time for the 9.30am Eurostar departure, or afford an overnight stay in London beforehand (perhaps a trip on the London Eye, which is next door to the Eurostar terminal), the train service is the way to go. Have you considered driving to DLP? It is a very easy journey from Calais (we use the tunnel) and gives you options to stay either on-site of off-site, and the flexibility to easily see other things while you are there (for example, the new international shopping mall next door to DLP).
Finally, if you think that you will visit DLP more than once in 12 months, the annual passes to the park are good value, and gives you discounts on lots of things around the resort.
Regards
Rob