Will we have to dig out rubble or can we put topsoil over it?

The best way of growing on top could be in raised beds? If you have a search and a browse on this site, you'll see some photos and read about how others did it. Otherwise, I think it will only work if your layer of topsoil is really deep - at least 1ft, but 2 would be much better. If it's any shallower, the veg that needs more depth for its roots will struggle. Having said that, I'd have a go at growing runner beans up canes almost anywhere. As long as they get enough water and do not dry out.

Would be best to remove it, as much as possible. Unless you are going ot go for raised beds and 2 foot would be enough. But the trouble is rubble will let all rain throuhg and you wont have many worms in the soil which are what you need for good soil

well if theres tons of it then maybe raised beds but if your up for a good bit of digging over most plants as allen titchmarsh so rightly sais most plants naturaly have to deal with stones

darnit, I'd overlooked the worms.
How did that happen? I've always liked them so much.

If you want to grow root veg, potatoes, carrots, parsnips etc. then your going to need a deep bed of soil. I would definatly take the weed control fabric away and as much of the hardcore as possible but if your soil is a clay then put some of the gravel back in and mix it up well. This will improve drainage and stop everything becoming waterlogged.
Weeding, how could you ??
After everything the worms have done for us? Lol :~))

ow obviously take up the membrane i thaught that was obvious sorry

Ooops, sorry :~))

lol no worries

I would still push to get rid of as much hardcore as possible. Good luck :~))

YES I WOULD IF THERES LOADS

Thanks so much for the replies guys! I'll look into the raised beds, there are a few old railway sleepers lying around which might be useful..... Otherwise I think digging through it will be impossible without an actual digger. K

raised beds it is the sleepers are perfect