DS1(18) has had his fixed appliances on for over 3 years, but his were quite complicated. We are on the final stretch now. He has had very little pain. He has always accepted that if he wanted nice, straight teeth he would have to have a bit of discomfort to get them. He has never complained, or taken as much as a Paracetamol even when they have put the new wires in.
He is excellent at cleaning his teeth. He uses a child's toothbrush to do them, we did try his electric one but he preferred a manual. The Orthodontist has always been impressed with his oral hygiene. DS1 just gets on with it, he doesn't want to go through all this only to end up with cavities or gum disease.
DS1's braces are dealt with in hospital, but DS2 had braces done at an NHS Orthodontic practice. His were on just over a year. We were told the NHS only pay for the metal brackets. I very much doubt you would get anything else TBH, and I doubt the fact that your DD is an actors would make any difference either.