Many people have heard of TransferWise, they entered the market offering fantastic rates when transferring money between currencies. They recently rebranded to Wise.
Payments by bank transfer are the cheapest way to use their service, but you can pay by card too if that is easier for you which also offers a slightly faster service.
The service is transparant, you can view your trnasaction, transfer and confirmation in an easy to use portal.
Wise is authorised by the Financial Conduct Authority under the Electronic Money Regulations 2011 for the issuing of electronic money.