Good Morning Stewart,
My problem was T1SCC in the lower jaw right side; one might say diagonally opposite to to your problem and certainly the reconstruction will be different but if it is any help to you the surgery in my case involved the removal of a significant proportion of the lower jaw bone and rebuilding with a flap taken from the left arm. The flap consisted of bone, tissue and plumbing. Titanium plate was used to strengthen the arm where the flap was taken from and more titanium plate was used in the jaw reconstruction.
This sounds quite fearsome but was surprisingly much less painful than one might expect, whilst the flap felt like a sausage in my mouth for some weeks I soon got used to it.Overall the reconstruction was very acceptable.
There is always a risk that the flap will not take but there are several other places where a replacement flap can be taken, and the risk of rejection is quite small.
Time in surgery is of no consequence , you will go to sleep and wake up some time later;if 6,12 or 24 hours have passed you will not notice.Be assured that the surgical team will only go ahead if they are quite sure that you are fit enough to cope.
I was sixty eight when I had my twelve hour job, and not at all fit and I have other ailments such as hypertension and vascular problems so at 46 you should be in a much better position than me to cope with the extended surgery. I am now seven years post op and enjoying life.