I've had ground like this and it's a pia. You spend an inordinate amount of time shooting very few deer, occasionally seeing the odd, unshootable glimpse in the trees which keeps you motivated if not fed! Sounds like you're sticking to highseats overlooking grazing anyway but stalking through thick cover like usually ends up in bumped deer so best bet would be highseats over rides (if you can get them cut AND maintained).
With regards to shooting the grazing land - rarely much point this time of year when sheep are on it as there is so much food around elsewhere (and they'll avoid the sheep if they can). Come late winter when it's slim pickings in the wood (and the sheep have gone) hopefully you'll have more success.