SWIFT transfers usually incur a £25 or £30 charge for any amounts from £1 upwards. Your own bank should be able to provide you with the charges.
If you're likely to be doing more transfers in future have a look at Transferwise, Starling Bank, Monzo, Revolut or XE. They all offer transfers at a lower cost than banks.
There's a huge amount of information available on Google about this.