Egmont, the current owners of Tammy, have made a tentative foray into digital comics, which may make my own effort superfluous. So far they've only released Roy of the Rovers through iTunes, but there's some indication that they intend to follow this up with more of their vast back catalogue.
That's the good part. The bad part is that they are a bit pricey. £1.99 for a 'volume' of 26 pages, or what I like to call an 'issue'. I have no idea of the quality, but when I'm getting original comics for less than that, I consider that a bit high.
Update: It appears that there is a one off special of Misty coming our way in digital form in the not too distant future, presumably with different contents from the last Misty special, but no Tammy on the horizon yet.