Just reporting back to say that we had a lovely day and everyone commented on how nice the food was.
The weather was fab and the BBQ was a great success. Those of you who said that the adults would scoff the BBQ were absolutely right - 35 people consumed 61 burgers and 48 buns .
Teens loved the pizza ( done in oven )
I bought the brioche style burger rolls and everyone loved then .
The s'mores went down a treat , as did the ice cream and sauces / toppings.
I make a large platter of various cold meats and one of fish - mostly salmon and prawns . That was easy , looked lovely and was finished quickly .
I made 6 different salads ( including the pesto pasta someone mentioned uo thread - thanks for that. it was lovely ).
I bought 4 salads from M&S.
I made two puddings - fruit salad and chocolate cheesecake. Three guests also brought desserts so we had loads .
I managed to buy nearly everything from Lidl and aldi, which kept the costs down .
I was VERY lucky to find lovely burgers in M&S reduced to £1, so I only paid £16 for 64 burgers- a big saving . Although I spent some of it on lovely BBQ sauces and posy mayonnaise etc
Very little alcohol was consumed, perhaps 4-5 bottle of wine / cava. But there were lots of people driving - I'm sure it woudl have been a lot more if there were more adults and it was in the evening.
The only thing I woudl do differently next time was buy more coke / Pepsi and fewer other soft drinks.
And we needed more glasses. Although I had 50, everyone had a drink when they arrived and put their glass down , then needed another one later. I was endlessly loading and unloading the dishwasher and didn't have much time to eat or talk to people . Maybe next time I'll get some plastic ones .
So thank you everyone for your advice . I feel much more confident about doing it again .