Tubes and trains are going to be running (including the night tube service) so that people can get to the festivities, they are making sure people can get there to wave flags vomits , but it is likely to be rammed
There are going to be major road closures in central London on the day so bus routes that go through the centre are going to be disrupted or on diversion - worth checking which you'll need to use and having a look at the tfl website which has a page of all the transport diversions.