I've been a few times (I love it there), although I've only once actually stayed in a park hotel (the other times we went with Eurocamp and stayed in a campsite about an hour's drive away to save money).
For the sake of cost, my friend and I stayed in one of the cheaper hotels - the Hotel Santa Fe (a nod to our time spent in New Mexico on study abroad a couple of years earlier - although it was January and snowy, so not quite the same). It wasn't too bad, breakfast was included (and was nice - croissants etc.) and I think you got vouchers for dinner, but the evening meal wasn't great (seemed a bit like school dinners or something). They have free shuttles between the hotel and the park, but it's actually only about a 10-minute walk along the path between the hotels and through the Disney Village, so we decided to walk to the park most days (that way, we didn't have to wait for the shuttle to arrive).
If you decide to take the Eurostar, the train goes from London/Ashford striaght through to the park - you get off the train actually in the Disney Village area - only a few hundred yards from the park entrance, otherwise I believe they provide shuttle/coach transport from the airport to the park.
The only thing I will say about going in the summer holidays is that it can be pretty expensive and also very crowded (although, with the fastpass system, you don't have to worry too much about the queues). My friend and I went in an off-peak week at the end of January - £250 each for a 5-day Park Hopper ticket and 4 nights in the hotel. Despite the cold, it was a fun week because there was hardly anyone there - the longest wait for a ride was 5-10 minutes (and the fastpass machines weren't even turned on) and the staff let us stay on the rides and go around on them as many times as we liked (it was so cold outside that we spent most of the days on Pirates of the Caribbean because it was warm inside, lol)!
