I would go with 1/35. I think it just looks better than 1/72. For vehciles, Wespe Models has quite a few British vehicles from the timeframe. Tamiya recently released an Austin Tilly that I have seen done up as a civil vehcile as well. There is an early 1900s double decker British bus in 1/32 from Airfix that could be used as well.
There are lots of military trucks that could be converted into civil vehicles with not much more than a paint job as well.
Good luck.