Martin, good choice! I was originally looking at a Plus Four, but arrived at the Plus Six and haven't regretted it.
You will get draughts coming in through the doors, and maybe some water if it is wet. That's standard for all Morgans, I believe (except perhaps the Supersport). As John says these things can be slowly addressed, and that's part of the attraction.
Check the levels in the coolant expansion tanks (one on each side, you will need to open each bonnet one at a time), the levels tend to settle a little lower than the indicated marks on the tank, but you may need a dipstick to check these; I use a wooden plant support stick. If the tanks are really low or, heaven forbid, empty, then suspect a leak somewhere. I've never had a leak, and I'm now officially out of warranty, but I know MMC will still address the radiator issue under 'warranty' if I have a problem.
Have them demonstrate how the hood goes down and up, and note that the tenax press studs must be loosened before moving the hood frame ... you don't want them pulling out of the bodywork. On my P6, which also had low mileage for its age, the spring clips were a bu**er to get into place because the retaining mechanism was 'dry'. It may need some lubrication to ease the operation. Mine works perfectly now.
If you're buying from a dealer these last issues should have been identified and addressed.
Above all, and again as John says, enjoy the test run.
