"Barbecue type food I'd say with lots of different grilled meats, sausages inc veggie ones, buns, french bread, fried onions, mustard etc available, jacket potatoes with grated cheese and a veggie chilli to help themselves to, corn on the cob and coleslaw!"
This is the way I'd go - 30 years veggie here.
There's loads of veggie burgers, sausages, fillets, grills, patties etc now.
Corn on the cob, veggie kebabs (peppers, onion, tomato, mushrooms, aubergine, courgette...)
Potato salad, coleslaw, beetroot salad... Will be scoffed by all.