Hi Stu, welcome to the forum!, please take a few moments to post a welcome note in the newbie section just so we can get to know you a little better.
Congrats on buying a DT, i recently bought one as a restoration project, then i bought another one to strip for parts, if you have a haynes manual and a multimeter you should be able to test the resistance of your coil, as for sourcing one, yambits is good, as is ebay, alternatively i think i have a couple of spares kicking around