Looking to get into home cinema installation - what's a good wage?

Hi all!

I've been lurking here for some time and finally decided to join. I've enjoyed playing about with my own kit for some time, and decided I want to leave my part time job in retail and pursue something more fun. I've found a posting locally, and after a successful interview and look around I found the wage was under £30,000 a year, and according to this https://www.income-tax.co.uk/salary-calculator/ I'd take home £23,000 a year, which seems low to me. Does anyone here work in a similar position and have a better idea of how much it would earn? Thanks in advance

-R