Computer for new job

I am starting a new job in 3D art (making landscapes, planets, still life shots) and I need a new computer to help me get started. There is a job offering that I have got from the UK and it would be my dream job, but in order to accept it, I need a better computer capable of being able to make and showcase of all my work to date.

I have already brought some of the cheaper items (like the case and windows 10 OS) but because I'm on minimum wage it would take over a month for me to get the required amount of money to afford the computer I need and unfortunately, the job offer can't wait that long.

Check out my current uploaded work here: https://www.artstation.com/nuts99