I don't usually like to review gambling related websites, but I'll make an exception this time.
First of, I disagree with StrongInTheArm about the links. Underlined blue links usually convert the best with most target groups. I don't usually like the way underlined blue links look, but in my book the way something works is more important on how something looks like. But don't trust us, do a/b split testing with a few different link styles and see which converts the best.
Everything looks good, I can't see any obvious flaws. If I don't count the annoying animated buttons on the bottom.
But I would polish your copy. First of all, you say "that is aimed at providing unbiased". That's a politician talking. There are three kind of people you don't usually want to relate to: a politician, a lawyer and a crook.
Why not just say: "Welcome to Online Gaming 4U – an independent casino website based in the UK that provides unbiased and genuine reviews for top uk poker and online UK casino websites." However, that's rather a long sentence, you could think about breaking it to two sentences.
The Guarantee logo makes you relate a bit to the crooks. If you offer a guarantee, you should define it, make it measurable and real. Now it's just a piece of graphics that doesn't have any actual meaning, isn't it? If you want to make a guarantee, do one and write about it, or remove the logo.
Any experienced browser can see by hovering the mouse pointer over your Visit links that they are affiliate links. This can kill your website, you just lost all your credibility. "All this guy says is because he wants me to click his affiliate links to make money" is going on the visitor's mind. To avoid this, you should make your links look more like this:
http://www.onlinegaming4u.co.uk/out.php?site=titan, which would then forward the visitor to your affiliate url.
And by the way, there's no need to link to the XML sitemap from the front page. Just submit the sitemap to Google, there's no need to link it. To any visitor clicking the link it just looks like there's something wrong with your website.