As Andy says, maybe the best way to show your/our feelings about this legal demonstration is to 'send them to coventry'.
The knee jerk reaction to this tactic maybe that we are giving in to them.. but I think it may actually be the only way of showing your opinion as if you did watch and let the blood rise and shouted something at them, they are the ones with the 'legal backing' as they got their paperwork in first, you would only be 'inciting hatred'...
The march is to make a point in front of as much media coverage as possible and the hope of a small group taking offence and without thinking it through, attacking the march.
Well if nobody was there, would they not look silly, demonstrating to empty streets, the Police officers minding the route have to be there so don't count.
Would be really nice if the national media stayed away as well so the only coverage they get is a couple of inches in a local free paper that the locals will use to line the cages of their pets or wrap their fish and chips in.