I spoke to my accountant about this recently and he advised me to reconsider as "incorporating" has minimal advantages if your gross profit is fairly low.
There is extra expense and hassle as a ltd company and if the tax laws change then you could get a caning and find it difficult or impossible to get back to where you once were.
A cynic might say that Mr Brown is currently trying to lure the Sole Trader etc. into incorporating and once enough are in the trap then the current tax breaks will disappear.
A realist might say that, knowing this Government's track-record, it's inevitable!