right!!!!

i am trying to work out in me head how much of stuff i will need and want to grow for example if i want 10 cauliflowers how long do they last in the ground once they have grown or should i plant a few the a few a couple of weeks later

You need to take into account how long each crop takes to grow to maturity.

For instance, salad leaves should be ready in 4-6 weeks so you can definitely get in at least 3-4 sowings in the average year. Sweetcorn on the other hand needs nearly all of our great British summer to grow and ripen so later sowings would probably run out of time.

Others are probably in between; for example you can extend your picking season for runner beans by staggering sowings by a month or so.