I would like to create a website similar to www.dealtime.co.uk but I
would like to know what type of software or scripts I should use and
where I could find such kind of scripts or software, if possible I
like them free.

you will not get anything of the type for free, good luck

It might be hard to find free software, however, there is tons of
webhosting companies that as a bonus gives you web developing tools
and lots of free scripts ready to install in just a few clicks.

If you already have a hosting service but it doesn't include any
software or any preinstalled scripts, you can download and install
them yourself. For web designing I recomend Dreamweaver at
www.adobe.com for a trial and for the shopping cart www.cubecart.com
100% free.

They are pretty easy to install and use. Good luck with your project.