disc or insurance? I assume that the situation i have described is not legal but please correct me if i am wrong.
Do people just take a chance on the journey home that they wont be caught ?
or do the police understand the situation and are happy to turn a blind eye if the auction papers are shown?

If you get pulled over for some reason, all you have to do is show the cop youre auction papers, and they will tell you to get it home an park it till you get it legal, because for one thing you can't put insurance on a car you just bought an hour ago, and you will not have plates for it for the same reason.

Cant you get a tow,,,home with it,,,,

NO you have to get a truck to take it home for you.

You must have a valid tax disc displayed in order to drive on public roads, otherwise you will need to have it delivered by trailer. The car must be completely raised from the road, and not simply towed behind the other vehicle. The auction may allow you to collect the vehicle at a later date or time, giving you a chance to sort it out. Check their terms and conditions, or ask them.

As for insurance, you can get short term "drive away" insurance from various companies, and the cover can start immediately if required. Norwich Union do it with their HPI check scheme, or you can get it as a stand-alone product.

You absolutely can not drive an untaxed, uninsured car home, wherever you bought it. Don't take the risk, you'll lose it before you get it home if you're caught. The police won't turn a blind eye to you driving such a car. It's illegal and if the car hasn't passed it's MOT it could be a death trap.

Either tow it or use a dealer tag.

You can't drive on public roads without proper registration, tags, and insurance. The cops aren't going to turn a blind eye, they'll have a field day with you.