Hi, welcome to G o y, you will need to dig in as much garden compost, well rotted manure, bought in soil improver as you can get hold of, and then in early spring use a general purpose fertilizer, growmore is probably the cheapest, and is a good basic fertilizer, you can also add pelleted chicken manure in spring, Derek.

You don't say where you live, but if you are near the coast and are short of compost you can use washed seaweed (On my mind as I collected a lot this morning)

And if you do decide to use washed seaweed, keep some for the pot... Yummy, and full of vitamins, especially iron ;o)

Thanks for that. Live in shropshire so can get loads of horse manure! How long after I've dug in the fertiliser should I wait until I could start planting?

Hi, if you have well rotted manure, mix it in now, then a couple of weeks before you want to start planting out, use the fertilizer, you only need to use a hoe or hand cultivator to get it into the soil.
If you only have fresh manure, then pile it into a heap for 12 - 18 months, then use it in autumn, Derek.

Thank you all for your helpful replies. Will get cracking in getting the soil prepared!