Hi @jeremygadd
If they’re one off trips, you may wish to just enter them in the GBP value.
However, recording in EUR would give you a clear record. The first thing to do is enable multi-currency and add EUR to your list. There’s a guide on that part here, which also shows you how to create the invoice in that currency too.
When it comes to tagging the payment, if you paid it from a GBP account, you will need to use the ‘Log Payment’ button on the invoice so it can calculate the exchange rate difference for you.
Hope that helps, but please let me know if you have further questions.