i know IB has a demo account and very cheap brokerage but be aware of the risk as it's from the US. it's popular though
a great way to demo is to manually backtest your strategy. e.g. i've manually traded my share trading strategy while the market was both ranging and bulling. it was treading water while it was ranging, and bring profits while it was bulling. you'll go through loads of charts this way , without waiting for months to turn by, and you'll learn part of the craft. but be careful you don't cheat when you use this method (don't let yourself see into the future, but one tick at a time)