In reply to The Ivanator:
> 1. (possibly big problem) is the rental company say that to collect the car you need to put a deposit down on a credit card (...)
From my experience in Spain, Italy and Poland: a credit card deposit or equivalent in cash is a normal procedure. Or, you will be asked to buy extra insurance (often close to daily rate of car rental).
> anyone know if I'm likely to be turned away without a car (nightmare).
If you go without credit card of fat wallet with cash, it's a lottery really, so you may experience the nightmare.
Same with details like the paper counterpart for UK license: all companies on the continent that I used mention both parts are required, but you may be lucky. Once, renting car in Italy, I forgot the paper counterpart but nobody asked about that at Hertz' office, so I just ended up with a bit shaky telegraphing knees
On other occasions, I had to present both parts of UK license.
> 2. (just cheeky) the car will be supplied with a full tank of petrol which will be charged for on arrival
That is a pure scam!
I never encountered anything like this.
The procedure was always the obvious one, I get car with full tank and I'm supposed to return car with full tank,
so I fuel-up at a petrol station for a normal price. Unless, I return car not fueled-up, the I will pay for every missing litre and then it's not uncommon price per litre is 150-200% of normal one
Good luck!