With Glenmore Lodge though I think of you’ve not done any winter walking/scrambling before they would want you to take the winter skills course which covers navigation, avalanche safety etc but not really mountaineering.
I did everything in one course with Glenmore Lodge (about 25 years ago).
However, the most important skills by far are navigation and avalanche safety. If you can’t navigate across the Cairngorm Plateau in a complete white-out with 100 mph winds occasionally knocking you off your feet in the gusts, you really shouldn’t be out in the hills in winter in Scotland.
I used to teach students winter mountaineering in the Cairngorms (a long time ago), you’d see complete fear on their faces when we took them up onto the Plateau in zero visibility and made them navigate about blind; but after a few hours they could find their way about and realised it wasn’t that bad if you just kept your nerve (and knew what you were doing).