If you've got a fish wholesaler anywhere nearby, you can get shelled king prawns for a few quid for a big bag. Let them thaw and then marinade them for a few hours in the following:
light soy sauce
dry sherry
lime juice
grated fresh ginger
garlic
a generous shake of tabasco
Bloody delicious and always get rave reviews when I have a barbecue.
Chicken tikka is easy, too. Tesco do a mix of tikka spice (or used to) and all you do is stir it into yogurt, then coat the chicken pieces in it, leave them in the fridge and chuck them on the barbie. I used to do it with chunks of chicken breast and cook them on skewers, but I'm posh like that. At least until the 2nd G&T.
And really good butcher's sausages always go down well.
I could also give you my recipe for Killer Pimms, but the Health & Safety Executive have expressed concerns following my last barbie.
One friend had to go to minor injuries, having failed to stop at the bottom of the drive and slammed into a tree across the road (he was on foot, not driving) and another fell down my front steps and broke a wrist, but was too pissed to realise he'd hurt himself until the following morning.
And someone took a tumble in the bathroom and fell against the pipe that takes water to the cistern, causing a leak.
Apart from that, I think everyone had a good time. 