Found this at my local Sainsbury's (Finchley Road, NW London), half price apparently, decent enough deal. Expandable by 1/3, the size is 54x35x17cm before expanding, expandable in depth to 22cm, well within the Ryanair limit before expanding, as well as other airlines I would think, but don't quote me on that.
This is a 2 piece, one smaller bag which can be found inside.
The main luggage comes with wheels and handle, luckily i found it as I went to Ikea as someone suggested (here) about cheap luggage, found nothing that I would consider cheap, similar luggage to the one I am posting about was around £40!
the small bag is w35xh27xd14cm (max), I guess it can be used to seperate things within the bag, documents, gadgets etc.
Lots in stock, in colours of black and pink for the ladies (or the brave men).