No licensing required in the UK.
I believe the vehicle is subject to approval by the government or a proxy.
I answered my question about the maximum lift coefficient. In order to meet the 20 knot stall speed at 365 pounds gross weight (70 kg + my clothed weight) the lift coefficient required is 5 for the geometry in the sketch.
Please show us your source.
Calculated CL 2.9 for a gross weight of 374lbs. Off to work so I'll answer better later