Disclaimer – I’m not an expert here, just someone who’s recently done this myself!
I’ve recently popped some beds into my back garden (about 15m²), I don’t have access to any municipal sources or local farms/stables with a supply of suitable composts/manure so I had to buy in a load of the 50L plastic sacks from the local garden centre.
I bought a mix of Durstons farmyard manure, westons Jack’s Magic all purpose and Gro-sure veg compost (roughly 20/40/40% ratio). Took a couple of trips, even with the back seat down and it took a week or two to get rid of the smell but pulled it off 🙂
I chucked it in on top of the grass, manure at the bottom, which so far (1 month on) has seen only a couple of persistent dandelion leaves pop through (easily plucked and fed to the guinea pigs!). I saw evidence of earthworms getting busy after about 3 weeks.
I’ve moved plants that were in pots into the beds, and I’ve already seen some significant growth on the broccoli and curly kale plants (which have been virtually dormant in their pots), and some lettuces that I planted from the garden centre have been providing a good steady yield, enough to keep two guinea pigs and a vegetarian wife fed.
Some spuds that I planted as a punt on the 9th to see if they’d be ready for Christmas have also come up with some good growth up to about 1ft already.
Pest wise, I’ve been struggling with whitefly at the moment, but I’m seeing some improvement after putting some potted pettermint and Thyme plants nearby. I’ve got some French Marigold seeds for next year to help deter them.
Hope that helps!