I'm a keen student of hammering foreign currency exchange costs down to the absolute minimum. I can confirm that Transferwise is really very good for smallish transfers like this. I used it earlier this year to pay for an apartment rental deposit in Tenerife. You effectively get virtually the spot rate.
Using the desktop PC version, you can also get £10 cashback on your first transfer when you sign up via TopCashBack (less currently from Quidco). Seeing as I only sent about £50, I effectively got an extremely good rate indeed.
Can't remember why, but I found for big transfers (£1000's), you're still better off using someone like FCExchange. I think it's because the fees rise with Transferwise as the size of transfer increases. But with those slight reservations, this service is recommended by me at least.
Whatever you do, though, don't use your bank for these things.