The single biggest problem facing English (British minus Scotland) politics over at least the next 3 election cycles ('15, '20, '25) will be the lack of any sort of cohesive opposition to the Tory Party at all.
Polls this week indicate that support for Scottish independence is growing and that by the time of the referendum, Alex Salmond will more than likely get his wish for the Cross Of St Andrew to be flying free and without peer over Scotland.
Once Scotland leaves though, the numbers in the parliament will change significantly. With all the seats currently held by the SNP and Scottish Labour gone, the Tories on current numbers wouldn't even need to be in coalition with the LibDems. This basically says that even if every MP were to retain their seat following the '15 election, that the Tories could kick their lapdogs (er LibDems) outside forever.
There are as it stands 650 constituencies in the United Kingdom, 59 constituencies reside in Scotland, however the Tories hold a grand total of one seat in Scotland. The Tories hold 306 seats in Parliament which in 650 is only just over 47%. If Scotland votes "yes" to independence, those seats immediately disappear leaving 591; 305 in 591 is a majority in their own right of 9 seats. The Tories could easily eject the LibDems from the Coalition and because the Cabinet would remain intact, even if a motion of either no confidence were tabled on the floor, or an attempt was made to block the budget, owing to Standing Order 66 which states that "the Commons would not vote money for any purpose, except on a motion of a Minister of the Crown" it would be disallowed.
I suspect that the LibDems are facing political oblivion. The party under Clegg seems happy to sit in coalition with the Tories and I suspect that the reason why they continue to do so is that they know that any snap election called before the term will result in voter backlash against them. The MPs of the party who currently hold seats in the parliament, know that they're in borrowed time and no politician likes the prospect of losing their own seat.
Labour themselves have their own problems. Unlike the 1870s-1920s which saw the formation of modern trade unions as a concept, Labour doesn't really have a base anymore.
The biggest problem is that since what little that was left of manufacturing in the UK was smashed to pieces by the Thatcher Government in the 1980s, there has been a generation which has grown up which hasn't really been represented by any political party. With the Blair Government in the 00s, Labour as a party has had its reputation damaged possibly irreperably.
On a more permanent basis, Labour and the LibDems even if they tried to form an Opposition Coalition would face the monumental task of unseating vast numbers of nominally Tory constituencies. Personally I think that the numbers are such that it would take at least two election cycles beyond '15 for another shift in British politics for a serious opposition to even raise its head; that is also assuming that both Wales and Northern Ireland don't catch the whiff of independence and demand to taste it themselves (though to be fair NI. always seems to send MPs in permanent opposition anyway because of an even deeper seated Irish Question).
Assuming that Labour and the LibDems did try to form an Opposition Coalition, they have 217 + 46 or only 263 seats together, after the 41 Scottish Labour and 11 Scottish LibDem seats were removed.
This might sound daft but I had to search back through the lists of results of elections all the way back to 1955 when Anthony Eden's government won the general election to find the last occasion when the Tories won more seats than either Labour or the then Liberal Party. Historically Labour only replaced the Liberals as the major opposition party to the Tories in the 1922 general election and only won government as late as 1924. The modern Liberal Democrats grew out of the Liberal Party who themselves were Whigs, Peelites and "Radicals" before about the 1850s.
This all generally suggests that Duverger's law which suggests that in a single member constituent system, a two-party outcome is the most likely, still holds. In conjunction with the fact that the UK has a hopeless first-past-the-post system, that Labour and the LibDems will be stealing votes off each other; ensuring that unless one of them dies or they merge, both will suffer. Hence my suggestion that it will take 3 election cycles to sort out and why I don't think that there will be anything other than Tory Governments until the General Election of 7th May 2025...
... plenty of time to destroy the NHS and kill the BBC, which is what Mr Cameron and his friend Mr Murdoch wants.