My non cycling friend wants a bike. £400 budget.
He’s a big lad and will be cycling round Bewl Waters.
I thought this would be comfier than a normal bike.

Define comfy.? Heavier, less well specked than a bike at a similar price point but would feel smooth if pootling around at a gentlemanly pace. The VooDoo Aizan 29er can be had for a few £’s more and is a better specked and lighter. If the lad can stretch to £450 the Voodoo Bizango (£500 – 10% BC discount) is a no brainer.