At the Coopculture website it seems possible to purchase a ticket and pay for an audioguide at the same time. I'm guessing it's not necessary as the audioguides can be purchased on the day but would it save time in queues to book them both in advance? Also, the website says I need to select a date which means that any flexibility regarding when to use the Colosseum part of the ticket would be lost. (I also - if I've understood other threads correctly - will need to go to the 'special events' window to collect my kids' tickets.) Any advice much appreciated!