Guy - your sheeting strategy depends a bit what is there already. If it's a weed-ridden mess (as my garden was when I started) then my way (the lazy way!) is to put down the black sheeting over the whole surface, and leave it til spring. Everything underneath should die. Then remove the sheets, put out your raised beds, add manure to the soil in them by the trugful along with compost and possibly grit if it's claggy clay, and give it all a good dig. As bookbook says, the digging part is hard work but well worth it. 
At my allotment, I reused the sheeting on my paths, doubling it over and then covering with wood chips. Alternatively, you could sow grass paths.
However, if you already have decent grass down the bottom of your garden and you want to keep that and dig beds into it, then maybe think about removing the turf just in the area of the bed and then sheeting that smaller area so you're not fighting down weeds.
In terms of your beds, have a careful think about what you like to eat, as this will really determine what you want to grow. You will probably want to have more than a single bed for veg, for instance!! Most veg growers will do a rotation that goes roughly roots (carrots, beetroot that kind of thing), then brassicas (broccoli, cabbage, cauliflower, kale), then legumes (peas, beans), then heavy feeders (courgettes, squash, tomatoes, potatoes).
This works well because each of those crops needs slightly different things. Roots like poor, thin soil that hasn't been enriched much. The next year, you add to the soil by digging in manure and lime and plant your brassicas. These deplete the soil a bit, so you add compost and leaf mould and plant legumes, which fix nitrogen. That gives you a bed that's ready for your heavy feeders, which like lots of richness (add compost AND manure before planting). And because they feed heavily, they deplete the soil ready for your roots again.
So a classic way to start would be to have four beds and to fit herbs sort of round the edges or in spare space (many are quite ornamental so work in flower gardens too). Salads can be grown as a 'catch crop', which is a really quick-maturing crop that you shove in around other things while they are still small, or put in troughs like book does with her lovely spinach.
Ideally, you want your veg beds in the area of your garden that gets maximum sunlight. For shadier areas, fruit is great to do -it's very easy and low maintenance and simply delicious! I'd think of it as a bit separate from the veg, though because in most cases it's more of a permanent crop. You won't want to be moving around your raspberries or rhubarb much! (The plants don't like it!) And, as I said, they do tolerate and even enjoy more shade.