Suggest the Georgian House in St Anne for a good lunch it's about 15 mins walk form the Airport in the main shopping St called Victoria St
Alternatively the Old Barn does a great buffet lunch on sundays you might a need a taxi for that but they're easy and cheap. It's behind Longy Bay and has a lovely sheltered garden.
Uplifting some cheap avgas will reduce your landing fee and the tower will call the fueller for you they usually ask on approach or just after touch down, but you can obviously request on first contact if you like.
The island is absolutely beautiful.
If you get a mail voice on frequency don't forget your High viz and remember to call for start up when you leave!