I stumbled across financial-spread-betting.com while searching on google on the subject. I am really a complete newbie where financial products are concerned and the site was a great help in giving me a first overview of the subject.
The site explains financial spread betting in detail including contact details of each of the main spread betting firms and the advantages and disadvantages of spread betting complemented by some history of the firms, as well as some feedback on binary bets (didn't really understand how these work though) and a section on gambling with a story of how an individual managed to ruin himself gambling lmao

As I've stated the site explains where you can spread bet - it also includes a very handy financial directory which i've bookmaked - i'm sure to be using this on a regular basis.