I've been using TransferWise recently (thanks to Firefly's post in this forum) but there is a relatively new service now available through Lebara Money who offer very good rates and a discount on your first transfer. It's a very similar offering to TransferWise so thought id let you know.
Their rate tracks the mid-market rate on xe very closely and at the moment there are no additional fees. There's also the ability to lock in a rate for 30 days although I've not tried that myself.
Transfers showed in my Sabadell account in around 36 hours.
This link gives you £15 off when you transfer £100. At the moment that equates to an equivalent rate of about 1.36 if you just send £100!https://money.lebara.com/raf/YR3DHR