Polytunnerls are good because they give you an extra two months on the growing season. You can start earlier.
The challenge with raised beds (if you use them) is mice and rats. You'll need to get some traps or they'll be in. You make a wooden frame and fill it with muck and good soil - perfect for them!
Food is earlier but the taste is (or should I say 'can be') less than stuff grown outside. Tomatoes seem to prefer greenhouses.
Don't pack your plants in to tight - they need a bit of room so stagger the rows. Get a book on forest farming and learn about different things in different beds. You'll figure it all out - it might take a couple of seasons - but you'll get there.