I've returned to work today after 5 weeks off sick with tennis elbow... total nightmare! Have been having intensive physio which is called inferential treatment but is basically an electric current passing through the joint to stimulate the blood flow (feels a bit like a TENS machine) and it has helped a lot.
The other thing to do is rest rest and more rest! I've been using my left hand as much as possible and as a result have broken loads of plates, glasses and mugs!
I find that sleeping with a pillow supporting my elbow helps as well.
Good luck with it, it's difficult to explain to people how painful it is! The good news is that it is self-limiting and will eventually go away (how long eventually is I don't know!)
Best wishes to you all