How to build a solid foundation with little money?

I’m 23 years old making between £1400-£1700 a month after tax working in a pub, I live at home paying £550 a month, I have a small credit card debt of just under £900, I’ve always been terrible with money (hence my credit card debt), I currently don’t drive but I’m taking lessons which cost me a little over £300 a month.

I’ve done tiny amounts of investing but only with small amounts like £50 as I don’t have £100s or even £1000s to invest and take a risk with. How can I improve my financial situation?