Self inflating are not that thick or comfy. The latest gen of inflatable from Exped, Thermorest are cracking. Depends on uses as to how light and thus expensive you want to be, and generally smaller. Uk weather something like an exped synmat would be fine for the summer or a neoair trekker. But they are pricier than your gooutdoors specials.

http://www.facewest.co.uk/Rollmats.html fave site of mine