I'm trying to collect information so I can mentally prepare myself

I was wondering what the average salary is in UK, for jobs like retail (fashion/body care etc..), automotive techs or service writers, security (although as a non UK citizen that may be difficult to get).
Any ideas? Just trying to figure out how much I would look at making and trying to figure out how much in rent I can afford... Can you say "STRESS"

Thanks in advance! Any insight would be helpful!
Also, what is the current minimum wage in UK?