Well done!
Potatoes are rather dull but they're brilliant as a first crop for breaking up the soil.
Most home grown vegtables are good but some taste spectacularly good when they're cooked strait from the ground - corn and carrots spring to mind - as do peas but you don't get much per square meter of those I find.
Ask around the allotment about second hand tools. People may be getting new toys for Christmas or may know people who need to get rid of stuff for other reasons.
You may find people on the allotment buying bulk seed if nothing else you'll get valuable information on what varieties grow best in the soil and conditions where you are.
Most importantly don't be put off if you have a few failures - some years are better than others for certain crops.
There are also a couple of magazines to look out for that are pretty good
http://www.growfruitandveg.co.uk/
http://www.kitchengarden.co.uk/