I was also put off by seed catalogues when I first started growing veg, and to be honest I thought Wilkos seeds were fine for starters (cheap & cheerful & great harvests - nothing wrong with them) It also gives you an opportunity to learn some skills along the way without costly disasters. By the 2nd year you'll be dying to try out new fancy varieties - all part of the learning curve
When considering root vegetables such as parsnip & carrots, take a look at your soil - if it is stoney or heavy clay, you might want to choose short fat varieties rather than long tapering ones.
Cabbages - a bit late for spring cabbage sowing, but look for varieties for summer, autumn and winter crops (I grew Greyhound for the first time and it was lovely and crispy, ideal in salads and a good introduction for anyone who says they don't like cabbage. Also summer Primo and a red cabbage Fuego - lovely solid heads and they keep well in storage. Last year I tried a savoy cabbage for winter cropping and it was nice - unfortunately I missed out on sowing them this year)
Peas - Kelvedon wonder can be sown early and like all peas should be done in batches for harvesting throughout the summer. Lovely sweet and tender. I also grew Hurst Greenshaft - again, a lovely pea but slightly more peas to the pod than the KW (was able to put more peas in the pan than I actually ate while popping the pods :oops: )
Sweetcorn - if you go for a sugar enhanced/super sweet variety, take care you don't plant them too close to other varieties as apparently their taste is affected by cross pollination (have to say I've not had this problem, but is usually written on most seed packet instructions) The other thing is to get them into boiling water as soon as you pick as the sugar content drops very rapidly. If you decide to freeze them, you MUST blanch them first, again as soon as you pick them