I would say take it and see how you go - we felt very overwhelmed by the size of our half plot at first, which we got about this time last year after about a 2 year wait, but were soon running out of space and are now hoping we can get another half plot - various squashes always take up any space you are not using (and sometimes space you
are using, as I have learned with BNS!). You can plant them through that black weed supressant fabric in any ground you haven't been able to clear yet, and you can grow unusual varieties that are either expensive or not available in the shops. They don't need much attention apart from the odd feed and weed! You can also plant fruit bushes for soft fruits that are so pricey in the shops, like currants, blackberries, gooseberries and raspberries. They are also fairly low maintenance from day to day and quite hardy once they get going. Some people also have a lot of success with strawberries, but I believe they do require more watering in dry periods than other fruits.
I must point out here that we both work full time, so only manage to get to the allotment about once or maybe twice a week, and the weeds sometimes seem to be winning, but all it takes is the odd extra couple of hours at a weekend to get them more or less under control for a little while longer.
It might be a little more difficult for a single person (you don't say if you have a partner to help) to manage a half plot though, unless you have more time than we do! I like the suggestion of sharing with a friend - why not ask around at work if someone else would like some of your space - half of your plot will be about 2 large beds or 4 small ones, assuming it is the same area as ours! Also remember you don't have to use it all at once - cover a large section of it with something to suppress the weeds for a year and slowly dig and plant in the other section, then gradually dig the covered section.
Our allotments have a rule that by the end of the first year you are supposed to have half your plot in use, and 75% by the end of the second year. It is not strictly enforced as long as you are making an effort, but it allows them to sort out those who are not making ANY effort, e.g. our neighbour who got their plot at the same time as us, visited once and planted one little bed then abandoned it, blighted potatoes and all! I do hope they enforce the rules in this case...