Honestly however much you want the plastic surgery, it is NOT worth the risk to go abroad. There are so many horror stories with surgeons messing up the surgery, not giving you the aftercare you need as you've already paid the money, and difficulties in ascertaining whether the surgeon is qualified or not.
Personally, I wouldn't risk it - save up until you can afford it on the NHS, have a consultation with your GP to see if there are any other treatments for your breathing, and really think about whether changing one part of your face will really change the way you feel about yourself, or will just allow you to focus on a different so-called 'flaw' once your nose has been done. This is how people become addicted to plastic surgery.
This page may help you:
http://www.nhs.uk/Livewell/Treatmentabroad/Pages/Cosmeticsurgeryabroad.aspxEdit: the website says he offers the rhinoplasty '
from £2050' - have you enquired about the price, as often with all the extra aftercare packages, it ends up being a lot more expensive?