Thanks Cod and Mike.
This is something I've had in mind for more years than I care to admit. I went with boards so I can add depth features like rivers/streams, beaches (maybe) and ditches. The basic array will be near 30 tiles all up - I have a lot of space for storage.
I have to say once I got started, it was easier than I thought it would be and everything just works. I suppose I find that when I think about doing something for long enough, I end up anticipating most of the potential issues. I do have a habit of putting things off and on occasion have been known to procrastinate.
I'm looking forward to generating 'specials' like hill-forts or specific an peculiar terrain features down the track. With about a week or two notice, I can add something for planned games without too much fuss.