Cheap Tenerife Car Rental

I have the old type licence green sheet in a plastic wallet.
(not the photo type)

As long as its a full licence, I’ve always used http://www.carjet.com, have a look at their website & they have an excellent ‘help’ section if you need more info. Always have your passport on you in Spain, apart from when swimming! [...]

I have read that a Green UK licence must be accompanied by an International Driving Permit.
Is this true? and if so where do i get one?