CFD's are a good way of using leverage to increase your exposure. The fact that they are leveraged(you are lending cash or scrip from the bank) means that your losses can exceed initial capital and you can very quickly owe the bank money, if you are not careful.
I use SBK online share trading, because they offer a wide variety of instruments including CFDs.
I suggest attending a few seminars on CFD trading (SBK online share trading offers them, as do IG Markets) before getting in.