Upvote:7
If your trip is on or before March 29, the visa should be free of charge under the EU free movement regime. If the trip is after then, it might still be free of charge, or it might not be, and on top of that there's a chance that the current Gibraltar controversy leads to a requirement for you to have a visa as well. It's not really possible to say at the moment when the UK will leave the EU, or even whether, or what the arrangements will be after it leaves.