I use
www.worldwideinsure.com for car top up insurance. You can select worldwide cover and if you google discount coupon for worldwide insure you may get lucky. I paid just over GBP 42 for 12 months coverage and its pay and claim. Been using it for years.
I also use
Car Hire from £4/day with Auto Europe for car rental. Find their prices excellent and service too. Prices seem to be a bit cheaper than the .com version of the website
Good luck and enjoy
Rgds
J