I have had an electric wchair for ten years. Before that, I used a manual.
Firstly, the NHS wchairs are bulky, heavy and difficult to get into a standard car. Do you want a manual chair or an assisted? There are loads on the market, my advice is to look on the health websites for a model you like then go search for that model on Amazon etc as some health websites quote inordinate prices.
The 'sportier' manual chairs are more expensive but they don't usually have that much more benefit other than being heavier. BTW the Red Cross will loan you a chair for a small donation (I think I paid £10) so you might try them and see how it fits re doorways etc before forking out on a chair that might not fit your circumstances.
Hope this helps and best of luck.