I recently check through a few and
transferwise.com and currencyfair.ie where the cheapest, but they use a new P2P exchange system. I used transferwise to exchange €9k with no problems.
Transfermate
Fees: % diff between spot & high street rate(might be 0.4% off spot rate)
Min tx: €1000
Transferwise.com
Fees: upto €300=€1, 0.0045% over €300
No min
Currencyfair.com
Fees:0.15% Match Fee, plus €3 transfer fee
No min