you will need to goto the dvla office to remove the disability class.

With regards to sorn, it gets reset when the ownership changes, so the new owner will always be responsible for declaring sorn - you may get away with it but then you may not.

I'd just phone them up and say you havent received a recent notification of sorn and you have had the vehicle for almost a year and have never had anything from dvla for sorn. i did that after a few months gap it all worked out fine