Turning a Lawn Into an Allotment

From the picture the area is quite small so I would get more raised beds then the question of soil is redundant.

Brilliant- digging up your front garden for veg!  Good luck

Could be a lot of builders rubble under that grass...

I'm all in favour of raised beds but I would still dig first. You can then get rid of any builders rubble you come across. You've got until spring to make a good job of it.

Stack the turf on one side and cover with a tarpaulin, as that will make good topsoil.
Double dig the ground adding manure, compost or whatever organic matter you can get hold of. Even if it is fresh manure.
Construct your beds, if that's the path you want to take (no pun intended). Add extra topsoil if you need to. If you get it dug soon you could grow a green manure crop over the winter to add more humus to the soil.

By next spring the manure in the soil will be rotting well, you might get some odd shaped carrots or parsnips in the first year but you'll be fine after that and the soil will be in good heart. The turf stack should be ready to add to the beds.

As has been said you will have all sorts of bugs in the soil that will munch your roots in the first year so don't get too disheartened if you lose a few plants to them, they won't like the cultivated soil so much after that and will diminish quickly. If you get your beds dug soon you can cut up some potatoes into chunks and plant them about six inches deep and put a cane where you put each one so you can find it again. Leave them for a few weeks then dig them up, they will attract some of the bugs which you can then remove and dispose of, repeat as necessary. Same with slugs using upturned grapefruit skins on the surface or beer traps.

Browse the seed catalogues over winter then halve what you think you want to grow as I'll bet you will over order    You can always buy extra seeds/plants next year if you have any space left. I would favour fairly robust veg in the first year, such as potatoes, onions, leeks. Leave the more delicate things like strawberries etc until the root munchers have diminished.

Have fun.