Kris initially used a whiteboard, but very quickly moved on to use Speak it on the iPad. This is a free app available from the app store on your smart phone. You could try practicing with it now so that you are used to it by the time your surgery comes around.
I'm sure the ward will have some aids to help as Anne-Marie suggests.
Tammy

Caregiver/advocate to Husband Kris age 59@ diagnosis
DX Dec '10 SCC BOT T4aN2bM0 HPV+ve.Cisplatin x3 35 IMRT.
PET 6/11 clear.
R) level 2-4 neck dissection 8/1/11 to remove residual node - necrotic with NED
Feb '12 Ca back.. 3/8/12 total glossectomy/laryngectomy/bilat neck dissection/partial pharyngectomy etc. clear margins. All nodes negative for disease. PEG in.
March 2017 - 5 years disease free. Woohoo!