Travel Insurance for World Cruises?

I am trying to plan ahead before the 2007 world cruise brochure comes out. This year's brochure for the 2006 world cruises lists travel insurance of £300 per person under age 65 for a cruise cost of up to £9,999 or £375 for up to £14,999. My own less costly annual policy which covers me for any individual worldwide trip of up to 90 days has a maximum payout on cancellation of £7,500. I have been looking online to try and find a policy costing less than P&O's with cancellation cover of over £7,500 without success. Has anyone found such a policy or do I face either carrying the risk over £7,500 or having to buy P&O's policy?