Based on the UK price transparency laws, the total cost your buyer pays (including booking fees) is displayed upfront for events selling tickets in GBP.
If you are selling tickets in the UK, you may want to avoid adding a transaction fee to remain compliant, and include any additional fees (such as payment processing fees or venue fees) into the ticket price itself.
This is not legal advice. If you have specific questions about your event’s compliance please consult an independent legal advisor.