Whether or not UK (or US) military are instructed to kill women and children is immaterial to the loved ones of the women and children who are being killed. And while UK forces aren't in Afghanistan to steal resources, they are there to help secure the route of an oil pipeline, and also to provide the US and UK with a staging point for other military adventures in the region. They're definitely not there for the benefit of the people of Afghanistan, who would prefer that they would leave. So people of that region have a perfect right to protest what the UK government and military are doing in that country. And since the UK is supposed to have free speech, they also have a perfect right to do it in the UK. Those who don't think they should have that right are no better than the repressive regimes they criticize in that regard.