Megan/Clio - 3 month insurance cover - barneybear

Hi all - piece of advice being requested: My car insurance on both family cars (Scenic and Megan) is due for renewal on a multi-car policy, me and wife on both cars, with the addition of 18 year old daughter on the Megan. However 1st March 2012 the family Megan will be replaced with company car Clio. Does anyone do a 3 month policy? Are there better options. Current annual costs appear to be £1400 for Megan, £280 for Scenic then take a cancellation fee hit for the Megan of £57. Advice always appreciated.