Bag advice

Does anyone have any recommendations for a bag suitable for say just a K-x and a 18-135mm lens as well as space for a 8" tablet plus space for a few small items. I want something that is designed so that getting items out and back is easy. I have been looking at small backpack-type bags but my concern is that it would be a faff to get the camera in and out. Any tips folks?

The bag must be able to withstand rain too!

Have a look at the Billingham Hadley range. Compact, slim to the body and room for a tablet as well.