What's the best used, small, automatic car?

I'm looking to buy a used, automatic, small car for my 22-year-old son. It will be his first car and our budget is £3000 - £4000. Ideally it will be a low insurance group, but I mostly want you to recommend...

What mid-size, automatic can I get that's reliable and cheap?

I've just passed my test and would like to buy a cheap, reliable, mid-size automatic (about the same size as a new design Vauxhall Corsa as it's what I passed in). As long as the automatic gearbox is known...

Which automatic gearbox is more reliable?

What is the more reliable choice secondhand, the VWG group 7 speed DSG or the E-Tech Renault Hybrid gearbox in the Clio?

Can you recommend a reliable and comfortable car?

Can you help me choose? I would like a medium size car, top priority is reliability but would like a good size boot 370+ltr, automatic and comfortable seats as I have a bad leg. Around £19k.