Hello MikeSandra. A campervan is traditionally a small VW conversion and I can't think of any that would have enough room for a u-shaped lounge. In the next category come small coachbuilt motorhomes and panel van conversions [PVCs]. Above this, come A-class motorhomes, usually with a drop down bed in the cab. If you want a rear lounge within 6m, you are probably looking at a small coachbuilt or a PVC. There will be more to choose from in the PVC ranges.
Automatics are rare although the recent Fiat Ducato ranges has an option called 'Comfortmatic' which is a robotised gearbox but not a true automatic. You will find true auto boxes in Mercs [tend to be large motorhomes] and old Ford Transit based ones. You can also retrofit 'clutchless systems'.
Campervans/leisure vehicles sold in the UK vary enormously in value from a second hand one around say £5000 to a brand new 'liner' at £350,000. An indication of budget will help narrow that down!
Based on the minimal information provided, I would suggest looking at Fiat based PVCs with the Comfortmatic. If you buy new, you can specify the Comfortmatic, if buying one a few years old, you will find some but most will be manual.
I have 6m A-class with Comfortmatic but no U-shaped lounge.