I recommend you test ride a Wisper Wayfarer, several dealers around London, their design office is in Kent, and the bikes are imported from China. This is a new model and so the difficulty is getting hold of one, the owner reports he has sold 3,000 and is quoting delivery in spring 2021. Available with either hub or mid-drive motors, the mid-drive model in standard configuration plus the optional 700wh battery pack is GBP 2,549 though reportedly prices and delivery times are going to rise, and with the larger battery weighs 29kg/63lb. The mid-drive has a torque pedal assist sensor and a throttle, the hub drive has a torque sensor upgrade option. The mid-drive motor is a new one, the Wuxi TruckRun M01 the Wisper owner says it was designed by the Bafang Max design team. The motor has just started appearing here in the US on the Priority Current.
Might struggle with the weight aspect on the Wayfarer - the 7 model is 135Kg max load which only gives 15Kg cargo capacity.
Cube Touring or Kathmandu have 140Kg max load, again not so great carrying capacity with a 120Kg rider
Haibike Sduro Trekking 4.0 also limited to 130Kg
A Cube Cargo Sport Hybrid would give you plenty of load capacity (120Kg rider + 100Kg cargo) but somewhat out of budget https://www.cube.eu/uk/2021/e-bikes...argo-hybrid/cube-cargo-hybrid-sport-bluenred/
This Kona UTE might be worth a look / more research ref weight carrying... about on budget https://www.pureelectric.com/collec...ts/kona-electric-ute-electric-cargo-bike-2019 At least this one has a powerful mid drive and decent battery.
Around budget are the Babboe bikes... https://www.babboe.co.uk/cargo-bikes/filter/elektrisch--yes
the Pro Trike looks a possibility with its lockable front box and 80Kg cargo, but the seat limit is 100Kg https://www.pureelectric.com/collections/cargo-electric-bikes/products/babboe-pro-trike-e-374wh
same issue with the city-e, same 100Kg seat limit.. https://www.pureelectric.com/collec...es/products/babboe-city-e-electric-cargo-bike
It might be worth a discussion with Babboe on your requirements though - something like there Dog-e model may well be able to accept 120Kg rider if the cargo weight is <60Kg for example. They are one of the more cargo focussed brands in the UK.