UK travel insurance?

We are looking into our vehicle/travel insurance and thinking of making changes. Currently we have a Nationwide Flex plus account which gives us annual international travel insurance, vehicle breakdown cover and family mobile phone insurance.

Before we got our caravan last year, that worked well for us as we used to go on foreign holidays, but are holidaying in the caravan in the UK, at least for the next 2 or 3 years and are thinking it's not really as useful as it was.

We are wondering if it might be better to use the money to pay for Mayday for better breakdown cover for our UK caravan trips and our 2 cars. Since the NHS covers UK health care, our personal possessions are covered by home insurance and our caravan and equipment is covered by our Caravan Club Cover, do we need anything else?

We are using all Caravan Club sites as we like them and think getting UK travel insurance might not be worthwhile since in the unlikely even of having to cancel due to illness we would only lose the deposit which probably wouldn't exceed the excess on the travel insurance.

If we do go abroad or take a different type of trip in the UK we could get some single trip travel insurance and Red Pennant if we take the caravan abroad.

Is there anything else that we would be missing without UK travel insurance if we downgrade our Flexplus account to a regular one and take out Mayday cover instead for the UK?