Best sources for cars for sale

[mmarksx19]

I'm looking for a cheap to buy (under £6000) cheap to insure (just coming out of a 6 month totting up ban so will have a tt99 on my licence) automatic runaround and wondered where people find cars these days.
I was driving a range rover and the insurance will be, as you can imagine ludicrous with the tt99 so going to drive cheap to run cars for a couple of years. No point in spending much as it will just be a runaround.
I normally look on autotrader which seems to have a reasonable choice.
Piston heads has a lot less vehicles in this range.
Facebook marketplace terrifies me as does eBay but I might be wrong, it's just my perception
Anywhere I'm missing?
I'm savvy with cars and would do normal due diligence (car vertical type checks) as well as giving them a good once over but I won't have transport until I buy something so don't want to travel the country on trains and buses wasting my time and money on rubbish cars.

Thanks in advance!