DON'T ROTOVATE !!!!! This is really my most sincere advice. We took on an overgrown allotment a few years ago, got it cleared, then rotovated - what a disaster! All it does is chop up those perennial weeds into tiny little bits, all of which root and make huge great plants you will never, ever get out in ten years of weeding. We have read and talked about this often in this site, and the overwhelming advice is, do not rotovate. Cover the ground with black plastic and use a glyphosphate weed killer if you don't mind chemicals, it is the least of the eveils out there, be patient and wait until things are dead - or deadish in the case of some weeds that you cannot erradicate. The overgrown meadow part will probably respond well to constant mowing, it is surprising how well good grass comes back when the weeds get their heads chopped off, grass doesn't mind but most other things do. I would suggest you stick with the chop and glyphosphate route for the rest. For brambles you do best to dig them out and treat with root stump remover, I hate chemicals too, but there is a place for their use on very rare occasions, and this is probably one of them. Have fun, and enjoy.