What alternatives should I consider to a used Vauxhall Combo Life MPV?
If you need even more space than the Combo Life and its siblings can offer, you might want to look for a Ford Galaxy. It’s great to drive, and its third-row seats are spacious enough to take actual people. It doesn't have any clever storage solutions inside, though, and misses out on sliding rear doors, too. There are plenty of them around, though, so finding a tidy one should be easy.
Alternatively, try a Volkswagen Sharan or its virtually identical sibling, the Seat Alhambra. Both of them are huge inside, have well-appointed interiors and the benefit of sliding rear doors that should prevent your passengers from opening them on a car parked next to you.