I agree about the weed matting/plastic sheets that people lay down. I didn't have any in this garden thank goodness, but did in the last. I spent ages ripping it up, trying to get the soil back in a reasonable enough condition to plant anything. Not only was it rock hard because no moisture could get down, but it was really sour.

I ended up digging lots of mulch and fertiliser in, and I also mixed it with good, rich soil. If you want to do that and you can't rob Peter to feed Paul (soil-wise), once you've dug it over...mix in a large bag of good potting mix. I had to end up doing that to one area when I ran out of other options, and I got a really good result that pleased me a great deal.

I'm sure that some of our other gardeners will have other ideas for you. Happy gardening.