Well I took the plunge and performed a full factory system recovery with my back up DVD's. Once Windows 8 was backup and running I finished all the updates for Win8 then ran the Win 8.1 upgrade and voila! the startup and shutdown issues haven't reappeared!
Just going to spend the next few hours (groan) re-installing all my software office 2013 and Bitdefender 2013 etc...
After reading a few forums on this I did try several attempts to sort this issue with uninstalling the likes of Bitdefrender 2013 and removing the intel graphics 4000HD drivers and reinstalling them but this didn't sort the long shutdown and startup times.
I've now a system that's starting in 45 secs to desktop and shutdown in approx. 55 secs! in my opinion Microsoft should have had a handle on this before so many were affected by rushed beta testing.