(from one who likes to get her money's worth)
I've just noticed that they've now added 'if clinically needed' on the NHS website. If they suggest a scale and polish - that proves it is needed (before you book the next one):
'Band 1: £23.80
Covers an examination, diagnosis and advice. If necessary, it also includes X-rays, a scale and polish (if clinically needed), and planning for further treatment.'
www.nhs.uk/nhs-services/dentists/dental-costs/how-much-will-i-pay-for-nhs-dental-treatment/
Price of books - Amazon the pirates!