We booked 1 night at Heathrow Holiday Inn Express with Meet and Greet Parking through Thomas Cook for £135ish. Thought this was quite good with M&G. Hotel includes continental breakfast. I think it's about 2-3 miles from Heathrow, but as our parking is M&G we will drive to the airport anyway.
A driver picks up your car from the entrance to the airport, or somewhere as close as possible, you hand over your keys and they take your car to an off-airport car park. On your return, you phone them once you are through customs, and your car is outside the terminal waiting for you. Super convenient, no hassle, strongly recommend!
We booked 17 nights parking at The Park Inn plus one nights accommodation before we travel - cost £100 (including £14 for morning shuttle & £3 cancellation insurance)
We have lure andy had the £26 Quidco cash back paid (considering a return taxi to heathrow is £180 for us this was a good deal - we just went for their 'mystery hotel' when we booked.
Premier Inn Bath Road with parking is £109 with partial meet and greet. They meet you at the airport on way there and take your car, but unlike a full meet and greet you have to catch shuttle bus to car park on your return home.
If the Holiday Inn Express mentioned earlier is the Terminal 5 one, then it's great, I stayed there last night (overnight parking £7.50), and £135 is a great price for full meet and greet.