Stop the Cuts - National Demonstration

This sounds about right, put forward what you believe in to the electorate + formulate policy in case of a hung parliament with differing compromises depending on the composition of any future government. All parties do this for every election.

As far as I know they are going to campaign as previously with their own agenda - and, of course, if they end up in a coalition, like any party, they will need to make compromises.

The LibDems had decided that if they went in to a coalition with the Tories they would be forced to drop their opposition to tuition fees.

No. Not the LibDems; a few of the LibDem leaders, secretly, without consulting the MPs who they knew were now campaigning on promises their leader had no intention of keeping. They could have decided this was one policy they were not prepared to compromise on; whether or not they were right to is another matter. That it was Clegg's decision is beyond doubt. So why would you not single out Clegg for your anger? And after him the MPs who decided to vote for the bill. None of them ever gave any indication at all that this was a policy they would compromise on (though compromise is stretching it when your policy is to abandon a fee and you end up voting to increase that fee).
Also, when you say "People need to be realistic" isn't that one of those debating tactics you normally deplore? Realistic in this case being whatever* you* decide it is?