This is difficult not know what she likes, however if you are going on a picnic, chicken is always a favorite. You can add sides if you like such as potato salad, or a nice bean salad. I think that a dessert would be the icing on the cake, such as a chees cake, or raspberry tort. My suggestion is to purchase your food items already cooked, that is unless you are a good cook and can master the flavors. Don't forget the alcohol, definitely champagne, Freixenet is very good quality at a low price. Good luck on your date!
Not a lady, but my recommendation:
Good charcuterie - Not salami, but sopressata, prosciutto is popular, but not my fav and some other types.
Good cheese - I don't know if she would like stronger cheese like bleus, so maybe some aged Cheddar and some Swiss.
Maybe some fancy olives.
Wine if it is allowed and you are of age - Don't know her preference but a semi dry champagne goes with everything!
Some bread to put it on...
Maybe some chilled grapes...
Most higher end groceries have entire sections for these types of meats, cheeses, and olives. Use your best judgment or just ask her what she likes.
You can bring some small sandwiches with different fillings (no strong cheese or tuna though if you think you're going to kiss!), pasta salad, strawberries, and seeing as it's her birthday, some cupcakes, it'll be extra special if you make your own. You could also find out what her favourite foods are and try to include that, she'll really appreciate the effort.
Maybe a few gourmet cookies or pastries. A few fancy cheeses and grapes. Good bread is a must, so a cut baguette. A nice salad is always good to bring, and some cold cuts and condiments to create your sandwiches.
So this Saturday I'm going on a 2nd date with my crush to the beach to have a picnic but I have no clue what I should bring to eat... Plus her bday is on Sunday so I want to make this real special.. Help ladies!!!