With regard to the Thyroxine, there has obviously been an error in the transcribing of the drug dose from the GP prescription to the hospital prescription. The ward staff will appreciate you letting them know this and they can get the correct dose restarted. This does occasionally happen to some patients, but it is generally picked up within about 24 hours (with us anyway) by the ward pharmacist, who checks all new patient charts with their GP and dispensing chemist, or by the relatives informing the ward staff. Sometimes, some drugs have to be stopped because of interactions with treatment, or because the current drug may be the reason for admission to hospital.
The junior medical staff all change in August, and rotate every 4 months through their specialties, but the senior staff eg Registrars and Nurse Practitioners attached to the teams make the whole 'change' process much less stressful for everybody, not least the patient.