It is legal to fly along at 3000 ft, at <140kn above a broken layer of cloud provided you can see at least one blade of grass. You could be 1 foot under a solid overcast. Obviously this would not be sensible, as you would have no chance to exercise see and avoid.
The VFR minima allow flight in some very unpleasant conditions. It is up to the PIC to decide if his expertise and his aircraft equipment are up to the job on any given day. I often find that with a low scattered cloud base it is much safer to get above it and fly in the smooth air with plenty of margin above minimum safe, this can often be done VFR. The risk in this is the cloud may thicken and you need to be ready to get down through a hole if need be.
Rod1