Would a Weeping Angel float through space if it was in outer space due to no gravity or would the quantum locking stop it from being able to float? For example, some astronauts are studying the anti cyclones of Jupiter and a Weeping Angel appears outside their rocket, would it float or would it stay still and not float?
If you watch the Series 5 episode Flesh and Stone, there's a part near the end where the Angels are shown falling as the artificial gravity in the ship fails due to them draining its power. This shows that an external force can be exerted on an Angel to cause it to move, it is only an Angel moving of its own volition which is quantum-locked.
Just a brief scientific point, there is nowhere in the universe where gravity doesn't have an effect, as gravitational fields extend to infinity. What is perceived as "zero gravity" is actually falling towards a source of gravity with no other forces acting on you, so "floating" in space is essentially exactly the same as the Angels falling example from this episode.
You're misunderstanding the Quantum Lock feature of Weeping Angels. Quantum Lock doesn't make a Weeping Angel motionless because there's no such thing as motionless. Remember, motion is relative which depends on reference frames. So, for you, a quantum locked weeping angel would be at rest only if you are at rest with respect to it. If you are in a reference frame which is uniformly moving, the quantum locked weeping angel would also move. If you are in an accelerated reference frame, the quantum locked weeping angel would also accelerate which means external forces can accelerate quantum locked weeping angels (inertial force in this particular case).
What quantum lock really does is that it makes them statue such that it can't move its own body at will. That's it.
In your idealistic zero-gravity case, weeping angel would definitely appear moving outside the moving rocket. If weeping angel starts moving with the rocket such that it appears still for the observers inside the rocket, consider the two rocket situation; one is moving and another is still.