You don`t say whether you have access to a car or how far you are prepared to travel.
Ham wall has good wheelchair access,though you will need to obtain a key,more details should be avalable on the RSB Website
Ham Wall was brilliant - especially when I found I could drive right into the middle of the reserve to the disabled parking using my wife's Radar key to open the gates. That made it so much easier for her (and me). Highly recommended for anyone with a disability.
Saw plenty of ducks - Gadwall, Tufted, Pochard, Wigeon, Shoveller and Mallard, and Canada Geese, displaying Great Crested Grebes, and a Buzzard that we tried to turn into a Marsh Harrier without success. Heard, but didn't see, three different warblers - Chiffchaff, Willow and Cetti's. We tried very hard to see the Cetti's - we're not the first to fail, are we?
Wheelchair access at Greylakes is also very good, with a board walk all the way to an easily accessible and very comfortable hide. As we walked in we watched Carrion Crows buzzing and chasing off a pair of Buzzards over the road. At the hide we were rewarded with close views of a Snipe probing the mud, large numbers of Wigeon, Teal and Shoveller, and 8 Little Egrets. Another Buzzard was working the marsh, and a couple a calling Curlew flew over.