Re: Transferring money back to the UK
I think you got the best options listed there.
I used CurrencyFair myself, but Transferwise is similar. They are both peer to peer services, meaning they allow you to find someone that wants to convert in the opposite direction, mostly cutting out the middle man (banks).
The idea is that both you and the other person get a good rate for exchange.
In CurrencyFair you can specify the rate you want and wait for it to be matched even, although you can also do it instantly which basically matches you with the best offer already available (from the people that want to convert in the opposite direction and have specified a rate and are waiting for it to be matched).
UKforex I don't know.