golden - that's brilliant news! Congratulations!!
The first thing to say is: please don't worry! I remember when I started to grow veg, it was all very confusing. I tried to make charts and timetables of what needed to be done when, and ended up feeling a bit overwhelmed and muddled. Actually, when it comes to doing it, however, it makes more sense and things just fall into place. It's a bit like the difference between trying to work out a dance move from a book, versus watching and imitating someone doing it.
Tips? Get lots and lots of horse manure (free from a friendly local stables)!!
Seeds - I haven't found a vast difference between different manufacturers of seeds. Stuff from Poundland that is 6 packets for a quid seems to work just as well as posh Italian stuff in fancy packets. However, what DOES make a big difference is varieties. The RHS do a scheme where they give an 'award of garden merit' to certain varieties of veg seed, and these tend to have a combination of decent disease-resistance, a decent yield, and a decent taste. They're a good option when you are starting out, because crops that are faffy can be discouraging at the start. Grow things that will do well in your conditions - if you're on sandy soil in the baked East, you may need to choose different crops/varieties from someone like me who is on heavy clay in a part of the country where it is continually raining. (We haven't seen the sun at all this week - it hasn't stopped since Sunday).
What else? Well, if something can eat your crops, the chances are it will. Expect to be under attack from mice, slugs, pigeons, and all kinds of insects. Clever use of mesh and deterrents can, however, keep most things off! (We are all fairly organic, I think, on this thread).
Final tip - take it easy at the start - even a half plot is a lot to bring into cultivation if it's in a bit of a state. Weedsheeting or cardboard + mulch over the whole area will stop you having to battle constantly against unwanted plants, and then you can work on a bit at a time. Setting areas to fruit is a job that can be done over winter - most fruit's really easy to grow and tasty and satisfying so well worth doing.
And enjoy!! 