
There are lots of mobility shops where you could get some good advice on powered chairs and which would the best for your purposes (self-propelled or attendant 'driven'). Alternatively you could contact your local Occupational Therapists for advice.
If you have a branch of Shopmobility (usually found in one of the car parks of your nearest good sized shopping centres) they can also give you advice.
The only advice I would give is to be aware of how heavy they are - it's the battery pack that weighs so much even if the chair itself is advertised as being lightweight; also checkout how long the battery charge lasts - will it be enough to, say, get to the shops, do the shopping and get home again.