I have been to Butlins Minehead on a day pass during a half term break and have never stayed there.
I am not what you'd call typically middle class myself but I can tell you that the majority of people at Butlins Minehead will be, errm, now how can I put this politely,...chavs and mostly from Birmingham area by sounds of the accents
Sorry but there's not really any other way to put it.
Your kids will love it, ours did, but then they don't really look out for the sorts of things that adults do. They loved the pool (but were toally oblivious to the awful changing rooms), the rides outside, the soft play area and the entertainment put on by the red coats in the central pavillion, which included a magic show, singing dancig etc which was all very interactive.
We were very disturbed by a girl aged about 15 who was minding her younger siblings. She almost physically assaulted one of the red coads who was overseeig the soft play area because she was convinced that antoehr child had punched one of her siblings inside the playframe. She was shouting and swearing at the top of her voice and it was all very scary.
Oh, and yo can only buy burgers, chips, fish and chips, fried chilcken and chips, pizzas etc there.
If you're happy to accept all of the above, grit your teeth for your children's sakes and be prepared to not make eye contact with any other adults whilst ensuring that your children do not get into any scrapes with other kids you should have a great time.