I guess it depends on what sort of bike you want to convert but as an oxydrive user I can certainly recommend the CST kit which is on offer at the moment. I'm guessing you are not too heavy so the kit with pedelec plus throttle option would be a good option and is very easy to build onto a bike, as long as you have the correct clearances and mounting options for the battery.
Am guessing you live near the Cornish Alps, the oxydrive kit on my MTB gets me around without issues.