If all else fails, find the nearest Registrar General's Office, or Births, Deaths and Marriages. From there, check for your registered birth date and then go to the authorities.
If you have no success, then go to the tv stations and tell you have a wonderful new skin secret that will make you look 40 years younger. You will have the proof age wise at least. By the time anyone catches on, you will have made enough money to hire lawyers etc.
Hope this helps,
Fellow Time Traveller,
Never give up.Never,never,never,never.