Paulfireblade's comment is very fair. I saw an article once saying running costs equate to something like 20% of the boat's capital value. My view is that you need to look at any boat that you buy and think of all the things you need to do to it to bring it up to your satisfaction. You might...
In passing the Time and Tide Museum in Gt Yarmouth has a fascinating section on the history of lifesaving on the East Coast. Not sure it covers the Walton area though.
Honfleur is also lovely and a Port of Entry/exit. Immigration is arranged through the marina office (tucked away in a side street behind the town hall).
It was open last Tuesday when we were there. They seem to have put a load of chairs and tables into that blue chalet next to it which I don't remember before so usable probably in wet weather too.