Youth Achievement Awards are graduated, from the Youth Challenge at the lowest level, which is the recommended starting point, to the Platinum Award at the top, which you cannot take until you reach 16. However, you should remember that following the programme in its entirety will lead you naturally to this point at the right age. Each step is designed to be harder than the last and involve either new skills or honing skills you have been introduced to previously. In terms of the time you spend on the various tasks, you will have to provide evidence that you have spent increasingly longer on each level.
The Youth Challenge requires 30 hours and the platinum builds up to 120 hours of participation, which sounds like a lot, but it is done over a period of time and you will be having so much fun you wont notice the time go by.
After completing the Youth Challenge, you can step up to Bronze Award or stop first to do the Youth Challenge Extra, then onto Silver and Gold, before eventually reaching Platinum, it depends how the co-ordinators in your area organise the tasks.
You will need to find out if the Youth Achievements operate in your local area and if not, whether you can persuade an adult that it is worth looking into. Perhaps someone at your school would have the time to become involved, especially if they do not currently run the Duke of Edinburgh scheme.