If you are new to growing veg (rather than just new to having an allotment) I would suggest you grow what you like to eat. no sense growing something "high value" that you are not mad about because if it fails its doubly disheartening for a newcomer; equally I would not grow "fancy" things. Home grown carrots taste great (my kids would say they are much better than shop-bought, and I just chuck seed in and leave it be, so I'm definitely not doing anything fancy)
Next up for me would be Value and Flavour. Main-crop potatoes are a nuisance to store, often "sprout" in store, are cheap-as-chips (sorry!) to buy in bulk from a farm shop - where they have been in climate control storage so are in good condition. So personally I would give Main-crop Potatoes a miss - but First Early New Potatoes are a treat, and at a time when they are relatively expensive in the shops.
But Sweetcorn, straight from plant-to-pot is a flavour you cannot get from the supermarket - the Sugar starts turning to Starch the moment you pick it ... our Summer house-guests rave about my Sweetcorn, I happily let them believe that it takes years to acquire the skill etc etc etc ... whereas all you have to do is pick it and put it promptly in the pan
![happy :)](https://chat.allotment-garden.org/Smileys/green/smile.gif)
Asparagus is a high value crop, but it takes 3 years before you get your first crop, the ground needs to be well prepared (the crop will be there for 20+ years), so worth not rushing into. Having said that, the fact that it takes 3 years means that it is worth considering early on, similarly with soft fruit which may give you a little in Year 1 but will not really crop heavily until Year 2.
Next up for me is provenance. I like that fact that I know exactly what has gone onto the food we grow. In my case we don't use any chemicals (but only because we have not needed to, rather than because we are totally organic).
And lastly variety. I can grow varieties that aren't available in the supermarket. The supermarket produce tends to be bred to be easy to harvest (all comes at once), looks good on the shelves, and often that is at the expense of flavour. For example, supermarket Tomatoes tend to have thicker skins so they damage less easily.
What sort of state is the plot in? If its covered in brambles or pernicious weeds then that suggests a different Year 1 strategy compared to a fertile, lovingly cared-for, weed-free plot that has been handed to you on a plate!