What can I do as a citizen of the UK to not be complicit in potential war crimes?

We all are worried about the worsening situation in Gaza. What makes it worst is that the western powers are supporting the already 4th strongest military in the world to bomb a civilian population. As a citizen of the united kingdom, you can withold your tax money where there is a possibility of the money being used partly or wholy to support war crimes. You can find more information here.