We dont use rollers although other therapists swear by them. Clients worry that they are unhygienic and that's an issue for us with our client base.
For Hollywoods it's about how to stretch the skin rather than applying a thin layer of strip wax. I have done waxu training which was pricey as an investment but the training deal was free training if you buy heater and lots of wax (they travelled to me) - but it worked out great for me. (Their heater has a custom fast heat function which is essential, you can't melt their wax otherwise) Their manual and system is the best I've seen. I was an experienced waxer stuck at 30 min Hollywoods and I shaved ('scuse the pun) 5 mins off my timings instantly - still chasing their promise of a15 min wax though. I think their wax is excellent although it's expensive so you'll need to price carefully. I charge extra.
We also use outback organics which is a lovely wax and very economical in use. They are based in Taunton in the West Country. You can buy their wax without the training - but I wouldn't recommend it, like most new generation waxes, you need to be shown how to use it properly in order to get best results. They have a north training site, but it might be a bit far for you to travel - they do travel to you though which might be better.
