All the parties are not the same. As an example, in the Department that I work for, the parties have hugely different policies that would completely, and quickly, change the way that our major public services are delivered. There is much more difference between the three major parties than there was, for example, in 1997.
Anyway, vote; for those of you going out tonight, eg to Walkers, that might mean you need to vote early rather than late.
Anecdote: I was in the hairdressers the other day and talking about how busy we've been at work (election periods tend to be a fallow time for policy civil servants; but the people who are pulling together material to give to possible incoming governments are an exception to that rule). She said 'oh, could you explain to me what the point of this election is?' And I assumed at first she meant 'what's the point, all the politicians are the same, why bother?' but it quickly became apparent that she meant 'I have reached the age of majority without ever grasping the first shreds of a notion about how the country I live in is governed.'