Having sung the praises of converting existing bikes, I now have an off-the-peg bike I bought secondhand off the Pedelecs forum. It's an Oxygen eMate MTB and is really rather good. I paid c.2/3 of the original price and it only had 140 miles on the clock. Surprisingly, it is rather well specced with 27-speed Acera gearing, Tektro Auriga Comp brakes, a Lookin saddle and a supposedly bulletproof rear hub motor. The rest of it is well put together and, the greatest boon of ready-made bikes, the spaghetti is all concealed in the frame.
The battery life is vastly better than the supposedly same capacity one I got with the conversion kit and the controls offer six different power settings in each of three modes. It is also very fast. In Speed mode, level 6, I reckon 25-30MPH on the flat would be achievable, but battery life would be greatly reduced. I run it in Eco mode and can count on 40 miles range at an average speed of 18/19MPH. at legal speeds I'd expect 60 miles & I'm no lightweight.
Rob, a ride on the machine is always on offer...