@svengland: You may have seen one of my earlier posts? Yes, you can go back to playing tennis. I was back on the court (level 3.5, ladies doubles) 2 days shy of the 4 month mark. Powder puff serve, but true overhead serve. Around 6-7 months I was getting close to where I was before the surgery.
Considering that I had a torn rotator cuff, a bone spur, and an irreparably damaged bicep tendon that had to be severed, it proves that time, and persistence, does help.