Hi Joe,
You are planning some great experiences for your Walt Disney World vacation.
Be Our Guest Restaurant at Magic Kingdom is an enchanting location.
Disney's Perfectly Princess Tea is a lovely event, with many royal touches!
I personally would not recommend doing both of these in one morning on the timetable you are considering. They are also both such special experiences that I suggest that you try to spread them out across days. I also think that the practicality of making it from Be Our Guest Restaurant to
Disney's Grand Floridian Resort & Spa on that timetable would be troublesome. Be Our Guest Restaurant is located deep within Magic Kingdom, in Fantasyland. You would first need to walk out of Magic Kingdom to either a boat or the monorail to get to Disney's Grand Floridian Resort & Spa. When you arrived at Disney's Grand Floridian Resort & Spa you would then need to walk to the tea party location. To be comfortable, I would want to allow myself at least 60 minutes for this journey, and that would not leave enough time to truly enjoy Be Our Guest Restaurant, especially since you would have just gotten into the park that morning not too long before!
I suggest that you head over to Disney's Grand Floridian Resort & Spa the morning of your Disney's Perfectly Princess Tea reservation and take in the amazing lobby and outdoor areas at this resort. If you are concerned that your party might get hungry before the tea party, visit Gasparilla Island Grill at the resort for a quick bite to eat.
Please do let us know if you have any further questions, Joe!