Im currently registered in my parents name becosue i am 17 years of age. I want to change it to my name becouse of tax issues, i am not sure if you need to declare such things as cj and adsense earnings in UK. But im not sure if i can change it to my name because of age issue and any individual in UK is allowed to make 5.4k with out getting it taxed (approx) so i wouldn't have to pay tax from most earnings, if it needs to be declared. Has anyone had any similar issues and could you just say your 18? Its not like it says much on the check?
I'm really not familiar with how it is in the UK but you should be fine telling Commission Junction that you are 18. They probably don't check it and you are close enough anyway.
I'm not a tax professional & not from the UK, but generally if you make money, you need to declare it as earnings - there's no way around that. Talk to an accountant or tax professional to find out more. Of course, http://www.hmrc.gov.uk/ may have the answers to your questions as well.
In the internet business, your age is not a big deal. However, you can ask your parents about the tax policy in your country if they some some different tax for online income.