I found physics great at gcse, but it gets quite boring at a-level and i regret doing it (because i don't have the motivation to do it) if i were you i would take psychology over physics (if you already hate it), also in maths i wouldn't take the mechanics as you applied module if you dislike physics (there is alot of cross over) .
but take what you would like best and would find interesting and have the motivation to do well in (i don't have an awful lot of motivation in my a-level subject at the moment and i regret taking them, so don't end up like me, cause i am not going to do too well)