First time

Hi im a student with not enough time to try and set up a charity yet. I would really like to go out and collect for charities but im not sure on the law.

If i just got a collection box and asked for donations and give the cash to the charity i decided on would this be illegal or could i say that its not a registered charity and that makes it legal.

Also i would never do this! but i have always thought do the charities by law have to give all the money they make to the cause or can they decide how much they feel is ok.

Sorry if theses are stupid questions but it is nearly 3am and my brain is not working fully lol