If you are still looking for one, my son has one for sale off a Tesco delivery van. The "you shop, we drop" size - not a big lorry.
It also has a small freezer compartment.
Trouble is, we're in Yorkshire and you're in Wiltshire. But it would fit on an Ifor Williams flat bed trailer or similar.
Don't know how much he wants for it, but will enquire if you're interested.