Hello Erica,
The site is situated on a hill but there are quite a few flat pitches which if you asked the warden he would probably put you on. The main road around the site is tarmac which would be ok for a wheelchair.
As for walks i'm not quite sure, i know there is a village just down the road which has a pub and local shop but it is quite a slope down to it and might be a bit steep for a wheelchair?
Not far away you have Woolacombe (nice beach),Ilfracombe (small harbour to walk around and small town for shopping) there are loads of other places in the area to visit it just depends what you like.
If i remember right you can get a good reception with a digi box on the site as you are quite near to a transmitter.
Hope this helps
Paul