Why do you go for those huge, higher-education conservatories? For one thing, your piano playing skills are less likely to get you in the composition course of these schools, and these are not places for beginners. You should try something for beginners. If you don't know where to go, the best thing to do is either ask at a music shop, or send an e-mail to one of these universities/conservatories and ask them if they have any courses for a total composition beginner, or what kind of courses/places/teachers they would suggest. I am sure they will be very helpful and you will learn much more from them than you would from me about this, since I don't live around you and don't know places or courses to suggest. Alternatively, you could contact individual composers and ask them for lessons.
I don't think 24 is a late age to start composing - Birtwistle didn't start composing seriously until his late 20's. You might think that it gives you a disadvantage in that you have to catch up with a lot of things that other people who started studying earlier know or have learned, but it's not how much time you've got to learn these things, it's how dedicated you are in learning them and how much time and effort you're willing to spend studying these things. Of course, it's not going to be easy, since when you're 24 you're probably more busy than when you're 14, but nothing's impossible
Contact schools and composers/teachers around you, and ask for their help. They'll give you much more in-depth feedback on where to get proper education and which places will be good for you

Take care and good luck
