And thanks to the confidence SmallCentral has put in me I've grabbed a tiny tiny dcc decoder.
I didn't get it from digitrains in the end because of the friction they create by insisting on website registration and an implication that they'll only ship to a cardholders address.
It may yet prove a mistake, but I've ordered it from coastaldcc who took paypal and appear to be able to post things to my office with abandon.
If I can work out what track design software to use with osx and sort out a dcc encoder and booster to work with that java thing then I'm home free except for a lot of card, foam, flock and muttering
Thanks for such a warm welcome to this site and the awesome advice you guys have given me so far.