I have a very simple rule. Ask yourself, really seriously, if she was in the position to do so, would she do the same for you. Really ask yourself and maybe even ask her. That's the acid test
I've done the non imm o a few times. Again London was great but the exact one that I used doesn't exist any more (OX?) the non imm o multi now requires medical and police check. The latter is easy but the medical is problematic in UK