My first foray into veg growing (years ago) was with just a smallish greenhouse. Inside I grew tomatos, cukes, aubergine, peppers, chillies ( yes you can get away with them in the same space as sweet peppers ) basil, lettuce, radish courgettes and spring onions. I had a table on one side, underneath which grew aubergines, peppers and chillies with radishes in between and the basil, spring onions and cut and come again lettuce in trays on top. On the other side I had two tomato plants, one cuke and at the end a courgette. Running alongside the greenhouse I had a row of garlic and a row of onions and on the other side runner beans which I pinched out at around 4 ft so as not to shade the greenhouse. This all took up around 8ft x 8ft.