The Act is The Sporting Events (Control of Alcohol etc) Act, 1985. It provides that anyone "entering or trying to enter a designated sports ground", when drunk, commits an offence. The key word is 'trying' . It appears, from what you say, that you were 'trying to enter'. The fact that you had not yet presented your ticket or passed through the turnstile, or even pushed the turnstile, is irrelevant.
Lawyers here may cynically think that the choice of the word 'trying' ,rather than 'attempting', is deliberate, an effort to make the offence simpler to prove.
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