I would alternate between the fruit/cheese plate and the creme brulee, and maybe reward yourself one day with the ice cream. Don't get the sugar free stuff. If you're going to indulge, do it right. :-) If you want to limit the amount that you eat, load up on real fat, like butter, during the meal. The Weight Watchers meme of "drinking water and eating salad" to fill you up is hogwash. Fill up on a tablespoon of butter.
Since you're only a few weeks into low-carb/primal, the sugar will probably ruin/delay your metabolic healing process. But hey, it's a cruise. Live it up, and get back to better eating later.
5'0" female, 44 years old. Started Primal October 31, 2011, at a skinny fat 111.5 lbs. Low weight: 99.5 lb on a fast. Gained back to 115(!) on SAD chocolate, potato chips, and stress. Currently keeping food tracker.
I (try to) follow by-the-book primal as advocated by Mark Sisson, except for whey powder and a bit of cream. I advocate a two-month strict adjustment for newbies. But everybody is different and should tweak Primal to their own needs.