I had my Nissen done six weeks ago and feel really good. I bought lots of really nice soups, eggs and yogurts. In the UK they encourage you to eat normal food but just a small amount, with the exception of bread and beef, not allowed that.
I found that the pain after the op wasn't too bad, pain from gas in the shoulder was uncomfortable, but it passes. Made sure I relaxed lots after, something I normally don't do. You will feel extra tired for few weeks.
The other thing I would say is don't try to eat too much, I was eating too much, this gave me the feeling of still having reflux, I was so worried that the op had gone wrong. But it was just that I was trying to eat too much. Warm drinks are very good, too cold water can cause problems. It made me have a sort of spasm, so avoid too cold drinks and definitely no sodas.
I have lost 14lbs since the op, most people lose some weight due to smaller meals. I feel better and great to be off meds.
Good luck with your operation, the forum has helped me so much since my op.