I had a partial glossectomy (small tumour no reconstruction from arm muscle needed) with sentinal node biopsy in June 2020. The sentinal node biopsy showed up 3 positive nodes so had neck dissection as second op in July followed by radiotherepy Augist/Septebmber.
Recovery from the surgery was not too bad at all. I had ice cream within a couple of ours of waking up from the op, liquid diet for a few weeks - lots of homemade soup helped - then soft diet for a few weeks more eating was close to back to normal by the time the radiotherepy started.
Recovery from radiotherepy was much tougher - started to have a really unpleasent taste in my mouth from about half way through which made food taste unpleasent lost quite a lot of weight, (was overweight before so not all bad) and eating very difficult for for latter half of radiotherepy treatment and about six weeks after - subsisted for a while mainly on hospital prescribed ensure drinks (mixed with coffee and suger helped with taste for me). had a feeding tube for a couple of weeks at the end of the radiotherpy - was quite opposed to the idea of this beforehand but it was very temporary and actually really helped me.
Now, 4 and a half months after the end of radiotherepy I can eat and drink pretty much anything though still can't really tolerate spicy food.
Speech for me was close to back to normal by the time the radiotherepy started but them went backwards during ratiotherepy, but is now close to back to normal again. The speech therepy and dietician team are a really important supportive part of the process following their advice and exercises to stretch mouth and tongue and preserve swallowing function are really important s, l and r sounds were the ones i found most difficult -
I think recovery time probably does depend on the amount of the tongue they need to remove though mine was small and didn't need a reconstruction from arm muscle - I guess if the tumour is larger, recovery will probablly take longer. It can feel really frustrating at times, communication and eating are such basic things to have impacted - and i do remember moments - particularly after the radiotherepy - of wondering if things would ever improve - but looking back now where i am 4 months after radiotherpy is a whole world better than where I was just a couple of months ago.
Wishing your father best luck for the operation.