If you go to another orthodontist (sorry if i spelt it wrong) then they will take photographs etc, and if they think it's justible they will do it again on the NHS but if you're teeth are reasonably straight and you want them to just look 'perfect' then they won't do it on the NHS. I think it costs about between £1,000-£3,000 but don't hold me to that. I know it's in the thousands though, it might also depend if you're under 16 or 18 though.