The "worst case scenario," on the back of my mind, is the possibility of stroke/TIA, but in a chap your age, it's unlikely. (Have a look at FAST/ABCD2 score.)
Other possible nasties include brain tumour, again very unusual. A decent clinician should be able to reassure following a sifting of symptoms and an examination in the surgery.
My moneys on the migraine, but as obs states, it's not a place for internet diagnosis.
Visual field defects are likely to ground you initially.