Hi Tilly
I hope all goes well with your boat. Our last boat was 1989 60ft cruiser that we stripped it out and refitted. We started out by having spray foam insulation put in and built it up from there. We had a morso muiti fuel stove which was great and an Alde gas boiler to the central heating which wasn't. We were never cold just using the Squirrel, even when the ice was an inch thick out side. We fitted the central heating so it could run of the engine which was really good in the day time when chugging to dry the boat out and dry washing but no good at night when it would have been more useful.(cause the engine was stopped).
Our next boat which we are just about to start to fit out will have a solid fuel stove connected to radiators and hot water tank running on the gravity system. If it does not work we will retro fit a pump. We will not bother with an Alde.
I don't know a great deal but what I do know I am willing to share.
Graham