Then there are the medicines: have we got all the asthma pumps? The creams? Plasters? And should we take Raymond? What if he goes berserk? Though if we don't take him, we'll probably be contravening his human rights.
Transport is an issue. Coaches are fine. The children are strapped in and sick bags at the ready. Buses are OK, if you can keep everybody together on the top deck. But trains are something else, as my young teachers discover. Watch the platform gaps like a hawk, make sure your little treasures don't cause the general public to flee the carriage, and be certain no children are left on the train. My teachers manage all this successfully, only realising after a headcount on arrival that Sam and Oliver, absorbed in the contents of each other's lunch bags, have already headed out of the wrong exit.
At last, everyone accounted for, they take a deep breath and survey the armoury on the entrance hall walls - until Gregory mentions that his brother has some stuff like this at home.
It's a relief when the guide shows up to escort them through the palace.
"Who knows Henry's surname?" she asks brightly - if optimistically.
"Easy!" shouts Thomas, "It's 'Eighth'."
Aisha says no, she thinks it's something to do with chewing, and Harry eventually calls out "Tudor".
"Correct!" says the guide. The children punch the air proudly and hurry into the first bedroom - far too eagerly, as it turns out. Kevin, not noticing the rope around the four-poster bed, sets off a piercing alarm. Attendants run in, muttering about teachers who can't keep their pupils under control. The guide implores the youngsters to look carefully but not touch, and the group is ushered along the corridor to another, larger, bedroom.
All remains relatively calm until they enter the Tudor kitchen, where Sadie slips, bumping into Darren, who falls against a stand supporting a huge soup tureen. As it crashes to the ground, one of the teachers later recalls, it's like watching your life pass very slowly before your eyes.
"Good thing you're not living in Tudor times," says the guide to Darren. "They'd have had your head off for that!"
Back on the train, the teachers breathe a sigh of relief. What could possibly go wrong now? And then, what used to be called a Gentleman of the Road - well past the alcoholic point of no return - lurches into the carriage. He accepts David's offer of a crumpled tuna sandwich and offers a swig from his beer in return.
"Are you their teachers?" he grins at my staff. "Well, you're much too young. Ain't they too young, kids?"
Three stops later, my staff ask the platform attendant to intervene. "Oh, it's Bob," he says, peering in. "He always rides this train in the afternoons."
There's a visit to the Tower of London available soon, but my Year 3 teachers have kindly offered it to Year 4 instead.
Mike Kent, Headteacher at Comber Grove Primary in Camberwell, south London.