Take a look at the Woosh Santana3: good for up to 18st and hilly areas, £1,099.
The Santana has an excellent motor, Bafang SWX02, you don't need to change gears. Range about 50 miles with the 36V 15AH, 60 miles with the 17AH battery.
http://wooshbikes.co.uk/?santana3