Someone near me uses an old petrol Vauxhall Zafira and another uses an old Renault Espace.

The Zafira would be fine as a 1.6/1.8 petrol or 'non-Fiat' diesel, but the Espace is a different matter. I do seem to remember them being on lists as the least reliable car you could buy!.

As i said before, difficult to make suggestions without knowing how much space for tools is needed, but even a saloon car of some description might be worth looking at. With the tools safely in the boot and out of sight, it could be more secure. Also, there would be less noise intrusion into the cabin from tools clattering about.

Espaces very thin on the ground now. On Autotrader there is only one for sale within 50 miles of where we live (just outside Bath). They are very pleasant vehicles when running correctly but they were also complicated and quite expensive to maintain. The chain-cam 2.0 dci is the best engine but even as Reno fan I would say leave alone and go for the Vauxhall. It will be a lot cheaper to maintain and repair.

You could get the 'car' version of the Kangoo, Partner etc. Once you take the seats out of the back, the only real difference is that they have windows.

At your budget, there would be a better chance of finding a half decent one, as these aren't particularly desirable as secondhand cars so relatively cheap. There are also more petrol engines ones about.

Another option if you have a car as well, would be to fit a towbar and get a small enclosed trailer for materials, tools etc to keep the car good (and empty) for non work use.