I traveled to England recently but was denied entry because I didn’t have enough money to support myself for a three week stay. How much should I have if I only want to stay 5 days? I don’t mind staying in cheap hotels or even hostels. Would $1,000 USD be enough ? Is it necessary that I apply for entry clearance also?

Around how much would I need to travel around the UK for about a month? How much do buses, trains, etc generally cost? Any suggestions at keeping prices at a minimal?