I use Club Direct (http://www.clubdirect.com/) who provide worldwide health care cover, for cruising periods of up to a year. (Emergency/repatriation basis). Experience not an issue. It cost my partner and I together about Ł800 per year last time we took it out, a couple of years back. Not had to claim, so can't comment on this.

In the more civilized European countries you might risk no insurance and rely on the E111. We've had emergency health care in France on that basis. Fine, just the same as NHS, no cash needed up front, but we were eventually charged 10% of the total bill.