Extended warrenty on 6 year old van

We are buying a 6 year old Coachman pastiche 520 from a dealer. The van comes with a 3 month warrenty , a 12 month warrenty has been offered at £294. 

We will have used the van 3 times in the 3 month period and being a believer in sods law ,we think a 12 month warrenty a good idea.

I have not found another warrenty on line , dealer deals can often be more expensive.

Has anyone found a reliable warrenty provider and are they worth it or does the small print make them worhtless ?

Many Thanks.