Under EU regs you can transfer to UK bank accounts for the same cost as a national transfer, provided the amount is in Euro, less than some generous upper limit, and you have the IBAN, SWIFT and BIC codes for the destination account.
The only question is what the receiving bank will then charge to convert an incoming Euro amount into Sterling.
I've just done a Euro transfer to UK (free using AIB online banking!). The recipient told me to add EUR8 to allow for bank charges on their end. I think that may be an overestimate, we'll see.