I was in the same position a couple of years ago. I got mixed advise on CBF, some said they would not take a chance some people told me they had got through Customs, no bother. So, I rang the Turkish Embassy and they told me I must get my passport renewed. Ended up making an appointment and travelling to Glasgow and paying extra, got the passport in 4 hours and then went to the airport. I can say I felt I had done the right thing, as I would have been sweating all the way there on the plane in case I was turned back.