Domain Considerations...

Hi Guys I have been lurking around the boards for ages, and having been trying to get my head around domain names and transfers and registration periods, I'm currently looking to purchase a co.uk and prices seem to vary drastically.
I have noted that a lot of providers have quite high renewals fees, but have managed to round it down to three providers.

I know its not a lot of money to loose, and such should just take the plunge but has anyone on here used these guys and what are your thoughts?

.co.uk @ £5 for 2 years registration -> UK Domain Registration, Email Services, Website Builder - Siteopia
.co.uk @ £10 for 2 years registration -> http://www.names.co.uk
.co.uk @ #7 for 2 years registration -> Domain Name Search Results - LCN.com

Obviously price is important, but would appreciate some recommendations.

Thanks

Guys.