You are confusing me...Are you going to Disneyland in CA, or Disney World in FL? Both CA and FL will probably have better weather than the UK, but this is the 'rainy season' for CA. As for FL, it can be cold with frosts and can be rainy. The winter rains usually last more days than the typical summer thunderstorm. However, we used to water-ski a lot on Christmas Day so it can also be warm, but will not be hot.
Floridians probably won't be swimming in the pools or the ocean, but UK tourists or Americans from up north will have no problem.
Sauce, what do you mean exactly by the 'whole American in-your face' thing? I'm not offended, but if you don't like America, why go? Plenty of other people want to go can go then. Why not tell your parents thanks, but suggest you go somewhere else?
BTW, I never wanted to come to England as knew the food and weather were awful and it never seemed 'exotic' enough for me. I know that most of the food is awful and the weather is poor, but I've met so many wonderful people and I'm glad I'm having this experience....still look forward to going 'home' one day.
Who knows..you might even like part of it. Good luck