In a nutshell,

there is no progressive liberal socialist party.
After the last election, the party called the Liberal Democrats went into coalition with the Tories (an alternative name for the Conservatives)
much to the chagrin of many of their supporters their leader, Nick Clegg accepted the post of deputy PM, to become the Tory party 'tea boy'. He has almost destroyed the party and they have suffered badly in local elections ever since. The Tories stand for greed and lining the pockets of the already rich to the detriment of the poor, weak and elderly and enslavement of the working classes.

Their main rivals are the Labour party, once the voice of the
Trade Unions in parliament, but now emasculated, lacking positive leadership and trying to distance themselves from their roots. They are never as cruel to the less fortunate when they are in power.

U.K.I.P. is a relatively new, right wing party committed to the UK leaving the European Union and preventing immigration. They are regarded by most as the B.N.P. in blazers.
The British National party, (often called the British Nazi Party) has inspired many minor right wing racist parties, funded by the rich but appealling to the poor white working class (your white trash)

Hope this helps.