This will be very tight. Parade won’t finish until 3:30 and you then have to get to Epcot (with crowds that leave after parade) and walk through the park to Rose and Crown. If you keep these plans I would see parade by flag pole, then uber to Beach Club from Contempirary and enter Epcot via IG (Rose and crown right by that entrance). You may do it that way, but it is more stress than I would want.
I would say unlikely at best. Even if you wait at the front of the park you’ll be at the latest part of the parade as it takes awhile to wind around to the front of the park. Using bus or monorail I’d say absolutely no way.
If you use the suggested taxt/uber method… maybe. But only just maybe. I’d keep an eye open for a later R&C to open up.
In Frontierland! It won’t reach the front of the park til 3:45 and moving about gets a little tight in the minutes just after the parade. So depending where you’re at you might not see the end of the parade til 3:45. That, plus travel time to EP and then walking all the way to the UK on the other end of the park? Nope, too close for comfort.
Though there are those will will say you can arrive late but may just have to wait. I just happen not to like taking chances.