So you're moaning that you had to pay for an adult ticket, because (presumably) Lambo Minor is a minor, but then try to buy him a pint and when you can't you moan again?????? If he's a minor why are you trying to buy him a pint? If he isn't a minor why are you trying to get him in as one?
I'm not sure what ID they expect kids to carry to prove their age, I wonder if their Thomas the tank engine fan club membership cards would suffice?