You have received lots of good advice here, all backed up with sound reasoning and logic. I think you should write down your reasons for doing SW in the first place. Write them big and bold and put them in a place you can see every day before you go. Then write a second list, just as big, just as bold, about why or how following the SW plan will spoil your holiday. Stick the second list up next to the first one. Then over the next few weeks before you go you can read the lists, pick just one item at a time and allow yourself a moment to feel an emotion about that single item and gauge how extreme those emotions are. Good feeling? Bad feeling? Guilt? Pride? Fun and joy? Let these emotions help you decide your priorities and make a decision before you go about how much you will allow yourself.
Now try something else.... Imagine yourself back home after the holiday, tanned and relaxed and a several pounds heavier, now try imagine tanned and relaxed and just a few pounds heavier, now imagine slimmer than ever but frustrated and jealous of the other people around you who were eating the stuff you enjoy, and regretting some opportunities to try something delicious. How do you feel about these three scenarios? Guilty and uncomfortable in your tighter clothes or simply happy because you are tanned and relaxed and have thoroughly enjoyed a well deserved break and know that those extra pounds will be easy enough to deal with?
You have already stated that you don't mind a small gain after the holiday, and plan to do a lot of walking and perhaps even try out the gym available. Maybe the final decision will be, as many people have already suggested, a combination of letting go and sticking with it, somewhere in the middle Relax and enjoy your holiday, don't let guilt about big yummy meals spoil your holiday, but don't overdo it either.
Have a super fantabulous wonderful time, whatever you decide.