RT Trading in UK Prospects and Career Path

Hi everyone! I recently accepted a shift trader job for a utility company in the UK. I understand that util is a great place for me to learn and would like to stay for 2-3 years before deciding on possible career shifts to other companies (merchants, majors, banks, HF, etc.). Hence, I would like to consult the community on several questions I have:

-Career progression for a RT trader at a utility company in the UK (how long to move further out the curve, how transferrable are the skills? Would it be possible for me to move to EU/US/Japan power trading

-prospects in staying in UK power vs moving over to gas 

-What is the ballpark figure for power trader based on experience and role? ( not too many data points online, and I felt that I was lowballed but I still took it because I recognize it is a learning opportunity and what I would be earning in the future will dwarf 10-15k annual salary difference)

-any recommended topics I should read on (how deep my maths/stats knowledge should be and what recommended books/podcasts I can look into)

Thank you very much for your kind responses beforehand.