Those who were homeless in the UK, is it difficult to receive support?

Never been homeless so far in my life, so I know very little. The few places I frequent normally have two or three homeless people about. I'm not made of money but I tend to buy them food or drinks when I can, I'm very wary of giving cash to anyone as I'll never know where it goes.

Was just thinking, what is the support network like for being homeless in the UK? Are they're many homeless shelters? Can you only stay for a certain period of time? I'd like to educate myself rather than just assuming people do nothing but sit outside tesco.

Is they're anything else I can do to help?

Thanks all