Its illegal to drive with no insurance. If the current owner allows you to drive knowing its uninsurred they are comitting an offence and you will also be comitting an offence. Points and fine for both.

Getting insurance on a car you don't own is difficult (if not impossible) and expensive, insurance for short periods is very expensive.

Only solution I can think of is to take a friendly local mechanic with you who has trade plates and pay him to do an inspection and test drive. With luck you may be able to drive as well.

I think it best if OP fills in an application for an actual car on autotrader similar for what he is looking for to get a price. It could vary a lot depending on where he lives.

I used to do this quite often. My mother no longer drove her old Fiesta and when I visited UK I would get a week’s insurance. On at least one occasion it was Royal, a major company, and was accepted to tax the car at the PO. It was expensive if viewed on an annual basis but good value for a week; cheaper than car hire and without all the hassle that can bring. Because of admin charges one day’s insurance would be expensive compared to a week’s. I must say that when I last looked prices had gone up considerably though.

I am not disagreeing with skidpan that “getting insurance on a car you don't own is difficult (if not impossible)” in general but maybe these short term contracts expect this sort of situation. I had no problem.

I am sure that I have test driven cars on trade plates and that there will not be a problem; but there the seller owned or at least had for sale the car in question. Use of trade plates seems incredibly strictly controlled; not even allowed to drop your children off at school on way to work.

Just use something like this:

www.dayinsure.com/

Last time I used them it was something like £12 a day or £15 for the weekend.

I tend to think of used toilet paper and all car insurance policy documents of being of approx the same value. Car insurance is an industry at least in the UK that is engineered for profit basis with not anywhere close to the level of regulation that is really needed.