YOu will get tons of conflicting advice, some of it from me :-).... First year I'd go with some things that will provide a crop and get you going, with an eye on stuff you like, stay away from "hard" things like celery and expensive exotics.... ASk around site for opinions on potato varieties.... we all have our favourites adn some of us raise our own varieties from the seed pods you can collect in the autumn (see under "Exotic)... Ones I'd recommend are (in no particular order) Sarpo Axona (blight-proof floury baker but no use boiled) Lady Christl (great tasting first early) Rocket (incredibly fast to crop first early) Pink Fir Apple (probably the best taste of any potato from store, but the knobbles put some folks off )...but there are tons of other, if you like roasties grow some King Edwards, if you like chips then Maris Piper. Salads are generally easy, especially spring onions and they always seem to cost silly money... Kohl Rabi is easy and if harvested small makes a sweet alternative to a radish, plus it has some bragging factor with folks who don't grow cos it looks a bit strange (adn tastes delicious) ...I'd also suggest thinking about establishing a fruit bed for things like raspberies, gooseberries, blackcurrants etc.... Raspberries are always expensive in the shops and once you've got them you tend to spend a lot of time trying to hold them back rather than encouraging them any more.... gooseberries are easy adn impossible to buy good ones, they don't ripen off th bush and they're too soft to transport when ripe... smaes true of blackcurrants...
Carrots are easy to grow generally and if you grow Early Nantes it will be one of the best tasting carrots you've ever had..... they can suffer from root fly so you might want to think about fleecing them, ditto leeks.... If you're a veggie then there are a ton of climbing beans that you shell for the bean (in a way similar to broad beeans) but the easy one to get is the climbing Borlotti bean.. so indoors in pots mid April, plant out mid-May expect a harvest in August through October, leave some to dry on the plants and that's next years seed... they freeze easily and are easy to cook from dried too... Sweetcorn too, start at the same time and in the same way as the beans , take a camping stove to the plot with you so you can take a cob straight off the plant into the pan for lunch.... it'll ruin you for the stuff form the supermarket though....