Link to law for the UK regarding electric push bikes: https://www.gov.uk/electric-bike-rules

This was surprisingly straight forward, a screw driver, socket and a couple of allen keys were all that was needed. It maxes out around 15mph but with kids on the back I haven't been more than 10mph.
Front hub is easier and for me the weight shift isn't an issue as I'll be towing the trailer. The thumb throttle is great to help launch from standing or for short hills. For prolonged electric assist a peddle encoder would be better but I'm going to try this for a bit.

I realised a little late the CE mark is more likely China Export than European Conformity :/

Some affiliate links if you are interested:
OOoo shiny new Christmas present 1/4 socket driver:
UK https://amzn.to/38Xo27i

It doesn't go outside.. or anywhere dirty

The battery I bought:
UK https://amzn.to/2Vgrh5w

Hub motor:
UK https://amzn.to/2NHKEmR

Affiliate links:
Camera used: DJI Osmo Action US: https://amzn.to/3RrZB75
UK: https://amzn.to/3dTtCiN