Hello - I had exactly that problem when I first did a winter skills course at PYB a couple of years ago. We headed out looking for some old snow but had to turn back because the weather was appalling. We did do some ice axe handling works before heading down - we ended up doing some navigation training on the lower slopes and then some classroom exercises.
In the event of there being no snow they have a series of old railway sleepers constructed at a 45 degree angle to create a steep, very slippery slope (the sleepers are old and covered in slime and moss). You would not be able to stand on it without crampons!
Using that we were taught the various techniques of walking up and down slopes in crampons and using ice axes to assist with climbing. There also have some horizontal boards set up so you can use the front points of your crampons also.
We then looked at ice axe arrests using a novel method of a dry bag and a wet, grassy slope - something you might have done in the snow when you were a child. Not ideal really but the instructors are a bit loath to teach ice axe arrests because the focus should be on good walking technique and not falling over in the first place.
Admittedly, nothing beats the real thing but as a starting point, it's really rather good. If you were to do a course at PYB, I would not consider it until late January or February - I did mine in late November!
