Hello, ben-heywood.
I'd like to share some details about your concern. For now, we're unable to change the value of the payment to a different currency. However, you can create an invoice for € and receive the payment in £. Note: Make sure the payment is deposited to Undeposited Funds.
Once your payment is recorded, you can create a bank deposit to the € currency. Here's a sample screenshot for reference:
I'm also adding these articles that you can bookmark:
Please let me know if you need anything else. I'm just a few clicks away to help you some more.