Just two little practical things (but they are in fact of importance).
If you start taking thyroxine, get used to really taking that 30 minutes before breakfast, e.g. directly after getting up, before entering the bathroom.
Thyroxine is one of the very few drugs where blood levels are heavily influenced by a combination with food. And in your case, achieving a stable steady state is the goal.
The second one: if a contrast enhanced computed tomography is ordered, do have a thorough conversation with your endocrincologist about that, and don't ever let your GP or radiologist decide that. The amount of iodine given for that exam blocks any further radio-iodine treatment for a couple of weeks, if not months. So in generally thyroid cancer is seen as a contraindication for i.v. contrast in X-ray or CT.
Wishing you a fast recovery.