Hi, I dive full time in a drysuit when in the UK
(which is most of the time) and I have never, NEVER, done the PADI drysuit speciality admittedly I practiced on the 6 metre shelf at Stoney with some experienced friends before going to Jersey but I don't see the course as being a necessity. Sorry if it upsets people but this is my honest opinion.
Take your time, learn how the suit works and save your money for more kit.
Noel