Check out
www.batribike.com
I got the chance to test one of their Gemstone Granite electric bikes a while back when I was commuting 8 miles each way to work.
Simply amazing - I felt like an olympian on the climbs and I cut my commute down from an average of 42 minutes on my C'dale to just under 30mins with the e-bike.
Not all e-bikes are created equal though - look for the battery systems especially and the switching for the motor - the one I used had a torque sensor on the cranks so it would only give you assistance based on the effort you were pushing with on the cranks.
This massively increases the effective range of the bike. Static weight is high as you'd expect but it never rode heavy. I was very impressed - and I didn't arrive at work and collapse in a sweaty heap, unable to do anything for 20 minutes :-)
Best of all is that they have a base in Chelmsford so it would be easy for you to go and see them - plus they're ex r/c modellers and general all round good guys and if you speak to them, say hi to them from me.