Cycling UK have just added various pages on ebikes (or their email has just made me aware of them).
I haven't read through any of it yet.
Electric bikes and e-cycles advice | Cycling UK
Do you need a little extra assistance when cycling? An electric bike could be the answer. An e-cycle provides an added boost, helping people new to cycling to improve their health and fitness and allowing current cyclists to go further, carry a heavy load or maintain a faster pace
www.cyclinguk.org