I have my Toupet Fundoplication set for the 3rd of February and was informed that a pre-op assessment is only valid for 6 weeks. If that elapses then another is required before you can be operated on, however it's possible they'd just get it done on the day as it's not exactly a complicated procedure!
I feel your frustration in regards to work, I'm dreading mine being cancelled or postponed on the day as my manager has had to remove me from the rota for 6 weeks (never mind being sat in a pre op ward all day just to be told it isn't happening!). I'm looking on the bright side though, I'm 24 and there's no way I'd be able to afford this OP without the NHS. I've already got so much oesophageal damage that my motility is impared, and I can only imagine what would happen if I had to deal with this for another 25 years or more.
Here's hoping it all goes well now you've got a date.
Jon