Browsing a bit on the Internet, I found some information on car insurance covering more than 30 days abroad (EU countries):Aviva
: European cover - 180 days per year as standard, up to 90 days per tripBudget
: car insurance policies provides EU cover for up to 60 days - normally can be extended by calling the company.Endsleigh
: includes cover in EU for up to 90 days.John Lewis
: long term cover (up to 90 days in a policy year), and offer extended cover automatically. They also offer options for long term European breakdown cover.Saga Car Insurance
: Unlimited ? Be careful here as they sometime offer a different policy badged Saga Select via a broker panel. If this is the case check carefully the European cover being provided as it may differ from the standard offer.
I also found another list here
In theory many of the car insurance provider offer extensions that can cover you for longer periods (several months).