[T4 VIRGIN-1]

frank-a lot of people have used a company called e foam,think you can google it and it will link to ebay shop,they have a choice of foam depending on occasional use,heavy use etc,worth a try,some people use a matterss topper for that extra comfort
i was lucky i got my foam from a caravan that was being dissmantled and its been good on the little use its had so far,happy with it and it was free