A Ha!
Success. - Based on the
leeg method.
I've created an excel spreadsheet to simplify the selection and downloading of map tiles. Basically I input the number of the top tile of each tile column I want in a map from the tile selection website. I also enter the number of tiles I want from that column, and specify if any should be skipped (if they are water only they don't exist).
At the moment, the spreadsheet can only handle 10 columns - which is enough for mainland uk, but not including Ireland - I'll need to expand it to 13+ columns.
Advantages of the spreadsheet:
1 - identifcation of "water only" tiles is much easier.
2 - once set-up, all tiles can be downloaded using a batch command. The same batch file can be run each time the tiles are updated.
The spreadsheet then generates a list of wget commands to download the tiles.
I Copied the commands to a batch file - ran it, and all the tiles were downloaded. Unziped and then used sendmap to generate the img file.
Using this method, I've been able to select all 56 tiles for mainland UK and create a map file, based on the tiles from 3rd December.