first time gardner

You're not too late! Theres time to grow plenty from seed for eating this summer: Salad leaves (lettuce, spinach, rocket etc), radishes, carrots, peas. And for over winter from seed: cabbage, sprouts, kale.
I've only just planted my main crop potatoes which will be very late - you might have difficulty finding seed spuds in the Garden Centres though.

As well as seed you will be able to buy plants from the garden centres, tomatoes, pepper, courrgettes, marrows, runner beans etc etc - theres loads to choose from and tme to get them in still - grow what you like to eat