In terms of how much you should legally be paid in the UK based on your age, these are clearly covered on the relevant pages of this section (see the links at the bottom for more information).
When it comes to equal pay between sexes, people are less clear. The key question often asked is 'are employers allowed to pay different rates to a man and a woman for doing the same job?'
The answer to that question is an unequivocal no. The law states that it is not allowed for an employer to pay different rates based on factors that are deemed irrelevant to the job - such as whether you are male, female, married, single and recently has been added on the basis of whether you have had or are going to have 'gender reassigment'.
This ensures that there is a level playing field for all. The legal precedent is the 1970 Equal Pay Act that made it unlawlful to discriminate on pay and conditions for men vs women.
It is important to note though that there ARE occasions where a job can be offered to someone of a particular sex because it IS relevant to the job.
Such scenarios are few and far between, but some examples would be some particular jobs in single-sex schools or acting jobs that require a man or woman to play a role, and things like those who search you at airports - a man to search the men and a woman to search the women and so on.