You can do either. Visa on Arrival is MUCH SIMPLER

A friend and his wife flew from London to Turkey just a few days ago.  Visa on Arrival, US passports.

They sent their daughter to Oxford Summer Camp for a week - the parents went to Turkey for 5 days detour.  They were in England last Summer so did not prepare to spend more time there on this trip, decided to get away somewhere for 5 days.  Turkey was chosen on the short list.