Sorry to hear about your troubles Paul & i know how you feel,
I am also waiting on a scan for my right shoulder (I'm right handed or should i say ding with my right hand or try to!) as my GP & Physio both suspect Rotator Cuff Tendon but my Consultant thinks it may be Frozen Shoulder.
I'm not too bad during the day (Bearable once they keep giving me stronger & stronger pain killers & anti inflammatories) but the nights are the worse for me, Soon as i'm still/try to nod off it really flares up so get very little sleep during the night & by the time morning comes round i'm wrecked tired due to lack of sleep but once i'm up n about the pain settles down once i don't make any sudden movements so i hope your Op & rehabilitation is successful
Ken