For a limited time, you can join a special Creative Cloud plan designed exclusively for Photoshop customers focused on photography. It includes access to Photoshop CC and Lightroom 5, plus feature updates and upgrades as they are available, 20GB of cloud storage for file sharing and collaboration, and a Behance ProSite. And it’s just £8.78/month when you sign up for a one-year plan. This is not an introductory price, but you need to join by December 31, 2013. To qualify, you must own Photoshop CS3 or later (Standard or Extended version)
You can see more details and to buy the offer here.