I happen to know that a 68-113 UN55 is 240g (that's on my scales), which is pretty light for £12. If that's not quite as light as you were hoping for, I'd recommend saving the weight somewhere else maybe. I found that BBs are not a cheap place to save weight off a bike.
Next cheapest/lightest option I found was JIS this carbon shell one from velodrome. I think the 110mm size JIS is 220g, but not sure if that size would be suitable.