Hi LSH and welcome to the site
Firstly, plan your plot out - where do you want the permanent planting to go? That's the berries and the rhubarb. I'm not sure whether it's getting a little late for this year to plant these - someone else may know.
It is often recommended that beds are not much more than 4' in width so you can reach the middle without walking on the soil, so consider this when deciding how to split your beds.
You will also need to consider rotation. This is growing plants of similar types together, and rotating where they are found each year so that you don't get a build-up of pests and diseases in one place. You will find different rotation plans (3-year / 4 - year; also what goes together) on different sites but as a basic introduction I'd group together:
- beans, runners, peas
- leeks, onions, spring onions
-spuds, tomatoes, peppers (these probably better as a greenhouse crop)
-broccoli and any other types of cabbage
- not quite sure how I'd group carrots with the above plants.
It is generally said that courgettes, sweetcorn, salad leaves etc can go anywhere in rotation.
I have heard it said that onions and beans are not happy together, but otherwise I don't think anything really hates anything else.
Don't manure where you will grow carrots or parsnips or they will be entering the funniest shape competitions for you all year
![biggrin :D](https://chat.allotment-garden.org/Smileys/green/biggrin.gif)
There's lots of info if you click on the Info tab at the top of the page, it takes you to a series of articles including (I think) planning your plot, as well as monthly guides. Have a browse round there too.
Good luck! And don't sow things too early - many plants don't need to go outdoors before the end of May, and will get very leggy if started off indoors too early.