Yahya Rashid paid USD 1,400 for himself and four friends to travel to the Turkish border town of Gaziantep in February.
He stayed in an IS safe house but shortly before he was due to cross into Syria, he changed his mind and returned to Istanbul.
Rashid, aged 18 at the time, was then detained by Turkish police and deported back to Britain, where he was arrested on his arrival.
Police believe his travelling companions did cross into Syria and are still there.
More From This Section
"You told the jury you had never held a gun in your life and there is no reason to believe that is untrue," Judge Philip Katz told Rashid as he passed sentence.
"But goodness knows what you would have gone on to do as a foot soldier of ISIS" (another term for IS).
Rashid's lawyer Mark McDonald insisted his client had wanted to live in an "Islamic utopia" but not fight.