Rapidly progressive periodontitis

I have recently been diagnosed with Rapidly progressive periodontitis (RPP) from a dentist I visited abroad due to server pain. I was told the treatment would be costly and entail many appointments to a specialist dentist. Can I receive this treatment on the NHS? Would it fall under one of the bands (A, B, C)? Does it cost extra? How much? How long would the treatment take from start to finish (upper left & right side)? Should I book an initial check or can I simply book the treatment as I have already been diagnosed?

If anyone can help with any knowledge at all, I'd be ever so grateful.