Welcome,
What you are planning to do is a great idea, i used to live in Stoke-on-Trent and there was a steelworks there, "British Steel - Shelton Works"
I used to work there years ago (about 1990) with petrol strimmers cleaning up the tracks etc, there were several shunters going up and down all the time, the track is about a mile long.
I used to go camping just outside Shelton regularly in a town called "Sneyd green" which is where i was born, i have great memories of hearing the loud roars of the steel being formed late at night in the machines, you could hear it miles away.
Doing a steelworks is a great idea as a first railway, you will have fun with this.