Hey Alexandra! Welcome to planDisney. It sounds like you have a big trip planned soon and an add-on stop to Disneyland Resort sounds like a great idea! Let's get your question answered.
Theme park tickets can be
purchased online or in person at the Main Entrance Ticket Booth. However, either way, you purchase these tickets,
theme park ticket reservations must also be confirmed for entrance into the parks. This means if you are seeing that reservations are currently full for your desired date, it doesn't matter where you purchase them because you won't be able to secure reservations as well.
All that being said, don't give up hope! The
Theme Park Reservation Calendar is fluid. This means that the calendar is constantly updating and changing as Guests cancel and book reservations. It is possible for reservations to become available again for the date you are looking for. I've had luck multiple times finally getting a reservation late the night before the date I need. That's not necessarily feasible for everyone, but since you will already be in the area this may work for you. I recommend checking the calendar frequently every day. If you see your date pop up with availability, purchase the tickets through the
Disneyland website. I recommend doing it this way because you select your date to make your reservation in the checkout process. This means if your date isn't available you won't be stuck with tickets you can't use because you will know this before you complete your purchase.
Alexandra, I hope this information is helpful and you have success getting tickets and reservations so that you can have the best day ever and get to surprise your son. Please come back and visit us again if you have any other questions!
Carrie