Somebody correct me if ive go this wrong

but after rereading the ticket info the conclusion i came to was:

Season ticket holders can go to Box office Tue/Wed/Thu or night of game and get their ticket for their seat. So are we talking about 6,000? I would guess that 3/4 of this total could easily get to the ground and collect on one of the days above.
This would leave about 1500 from other areas to collect on the night.

Non season ticket holders can collect tickets in East Stand. Now i reckon about 9,000 non season ticket holders would want to watch the game. Again the majority would be from barnsley and surrounding areas so even with similar amounts from other areas or those deciding last minute say 3,000 would then have to pay on turnstiles if everyone local who could get to ground beforehand got theirs.

So with those maths we would already have over 10,000 with tickets before the night of the game sold within 3 days and a queue of 1500 turning up on night for their seats and the usual 3,000 or so turning up at turnstiles like usual.

All in all i think if you can get down to the ground before the night of the game do it if not it shouldnt be too difficult assuming the computer system doesnt crash.