Would going to the end with some stacks of blocks to setup a hideout/bridge to the main island before going in with all my diamond gear be a good idea? I’m worried about getting knocked into the void before getting onto the main island, or is this a non-factor?
You absolutely can fall or be thrown into the void when first arriving in the End.
Be aware that the only way to exit the End without first killing the Ender Dragon is to die, which returns you to your spawnpoint (i.e. last bed slept in, or World Spawn if no valid bed). You may wish to take an Ender Chest with you to stash important gear (it may get destroyed by the Ender Dragon but the contents are safe).