I can't imagine more than a few people with cameras for youtube turning up and being escorted away. It would be a bit pointless, with all the publicity there's a good chance anything of sensitive value will be long gone.
It would be a difficult situation if it did go ahead;
If people think it will only be warning shots so they proceed, what would the guards do.
The guards (who are human) would then have to make the decision whether or not to open fire on civilians, I imagine most did not sign up for that.
If the guards then have to open fire, it'll be a dark place for them mentally for the rest of their lives.
I've seen that others have since made groups for storm the houses of parliament and other silly ideas.