Hello Julien!
Thanks for visiting planDisney! I hope you're having a wonderful time in California.
Yes, guests are welcome to purchase theme park tickets at the booths outside the parks. But there is a bit of a risk in waiting to get tickets until the last minute because you need both a ticket and a theme park reservation to enter the parks and reservations can sell out. If you can, I would suggest
buying your tickets online as soon as possible so that you can make your theme park reservations at the same time.
The good news is that I checked the
Theme Park Reservation Availability Calendar and it looks like both parks currently have open reservations tomorrow. So get those tickets purchased and your theme park reservations made!
You'll want to link your tickets to your MyDisney account using the
Disneyland Mobile App. Then you can use the app to join the
virtual queue for two of the most popular attractions in Disneyland Park: Haunted Mansion Holiday and Tiana's Bayou Adventure. Both attractions do not have a standby line, so you must join the virtual queue to experience them.
The mobile app is also where you can purchase
Lightning Lane access. You can choose from a Lightning Lane for select individual rides, or the Lightning Lane Multi Pass which includes a variety of rides. Tiana's Bayou Adventure is included in Lightning Lane Multi Pass, so that's another way you can go splashing in the bayou!
Have a fantastic time at the parks, Julien!
Keep moving forward!
Amanda