I have been to both this year, and there is no comparison between the two ime!
Butlins (Minehead) - lovely staff, very very clean, loads to do that's included in price (waterpark, softplay, fairground), beautiful grounds, hanging baskets of flowers everywhere, beautiful beach across the road. Someone was sick and the cleaning staff masks descended with red and white tape to cordon it off and clean it up thoroughly.
Haven (Craig Tara, Scotland) - horrible, rude staff, have to pay for extra for everything, filthy dirty, fag ends and dog poo EVERYWHERE, pots originally for flowers empty and full of fag ends, nasty stony beach that you can't sit on. Weirdly, someone was sick there as well. The staff ignored it, and when I pointed it out to two different members of cleaning staff they both shrugged and walked off. Some seagulls ate it in the end.
I would never, never, ever set foot in a Haven camp again, but Butlins was really good, I was very surprised (although accomodation was shabby on outside, but spotless inside and very comfortable).
Could you borrow one of those blow up firs/junior air beds for your dd? I took ds's Ben 10 bed to Haven so we didn't have to sleep in the lounge, and it was fine.