you can quite easily narrow your choices down quickly.
UC Berkeley will be a LOT of work for no recognition, from your English university. It will however provide campus spirit and world class educational opportunities. To be honest, you would do well to get in there just for the semester, but you never know.
UCLA is similar to Berkeley in that it has that buzz, yes its football team arent as good as UCB by quite some way, but in literally every other sport going, UCLA rules. No. 1 college for NCAA championships in the country - the place oozes athleticism, and it has the academic credentials that only Berkeley can surpass, within the UC system. As you may be able to tell, Im a Bruin.
UCSD i dont know much about, but its well respected too, SD is a nice city by all accounts, solid academic choice but little else to it. dont quote me though, i dont know much about it as i said.
UCI is boring. dont go there, the only people that end up there are there because they didnt get into UCLA, UCSB, or UCSD. simple as that. its ok if you have a car, but do not whatever you do make it your first, or ideally even your second choice.
UCSB is another viable option, especially for a semester. sick parties all the time, ok academics, not too much work so i have heard and a stunning ocean location. i dont know how hard it is to get around/away from there when you want to, but its in between LA and SF roughly, so its ok.
so basically you have three choices - Berkeley, UCLA, UCSB.