Mike1975
Die EU-Mitgliedschaft hat damit nicht unbedingt was zu tun. Sondern die bei den SEPA-Ländern. Auch Nicht-EU-Ländern können SEPA-Länder sein -- Even non-EU-countries can be SEPA countries, so EU membership doesn't necessarily have much to do with it.
Back to the original question: While SEPA transfers should be possible to most (all?) UK banks, if the payee's account is held in GBP, sending GBP (instead of EUR) via TransferWise would probably save on currency conversion.