Upvote:2
There will be a check of your visa and passport as you arrive. How long this takes depends on many things -- the length of the waiting lines, the desire of the officer to take a coffee break, your appearance and demeanor. You should be able to answer questions about what you will do in Spain and when/how you will leave confidently and then your passport gets stamped. If you appear nervous, or different from the typical ILR resident, there may be more questions and it takes a few minutes more.
Probably the real difference will not be the length of your interview, it will be the length of the waiting lines at the various gates.
June will presumably be after Brexit, so nobody has any idea which rules apply to your boyfriend. It could happen that you will get through faster ...