This bit worries me, from one of the links you provided, it appears as it has 4 wheels it will be illegal
"The EAPC must also be fitted with a plate (where you can easily read it) showing the manufacturer's name, the battery voltage and motor power output.
It is interesting to note that whereas these regulations cater for pedal cycles with any number of wheels from two (bicycle) to four (quadricycle) – or even more – electrical assistance is not permitted with more than three (tricycle). This means that load-carrying quadricycles, increasingly used for deliveries into areas from which motor vehicles are excluded, cannot receive a little necessary electrical assistance without themselves becoming classified as motor vehicles"
Alan...