I know someone with some ground to spare which at moment they find difficult
to maintain. So some fast growing ground cover which requires little
attention would be good to keep the weeds at bay.

Recently I saw a fast growing squash with big leaves that covered the ground
quickly. I was told it was a japanese squash called Kabocha.

Looking up kabocha on wikpedia i see there are 8 varieties. Would anyone
know which one would be the easiest type to grow in the London area and also
which is also a good tasting one. Thanks for any advice.