Welcome to the the forum demo.
I can't really comment too much as I didn't start with a demo account and just went feet first into losing money.
If you are confident that you have a good strategy in place and it's making you money in your demo account I would try it out in a real account with small trade sizes and see what happens. Your not the first to say they've made money in a demo account only to go on and lose money in a real account. I think part of the problem comes down to our own psychology. When it's a demo account it's not real money and you may think you are doing exactly the same as you would with your own money but when it comes to it trading with your own money is so different. You will become disheartened when you make a loss and elated when you make a win. It's these emotions that can see people running losses and taking profits too early which is a sure fire way to lose money.
I think IG offer £0.1 trading for the first 2 weeks and then it increases after that. Also FinSpreads
offer £0.1 for the first 8 weeks I think(don't quote me on that). You're best to open a live account with one of these and trade small to see how you get on. I think you might find real life trading different to using a demo account.
If you do decide to go live please do let us know how you get on.
May the markets be with you!
The Spread betting beginner