BT have just this week installed fibre to my house. While most of the last mile is copper it is wrong to say "Everything is copper" particularly when you consider in a vast majority of cases now the cable from exchange to the cabinet is fibre.
With UE4 you can pay for a single month and retain full access to the tools you've paid for, you just don't get updates. What you could decide on doing is paying every few months when an update comes along that offers something you need / want.