A few years ago, New Labour offered Thatcher the first state funeral for a PM since Winston Churchill, as if to further underscore their non-socialist credentials. Meanwhile, anarchists and socialists of various stripes have, for some years, been planning a massive party in Trafalgar Square on the Saturday after her death. I imagine the police are aware of this and have made plans to deal with it.
I can see why people whose communities were impoverished, as if in a campaign of collective punishment for having supported Labour, by the somewhat callous way Thatcher presided over the economic readjustments might rejoice in her passing. though, given that Britain is facing the most severe economic cuts since 1918, I imagine their celebrations will be somewhat muted.