LukeD, I hope you haven,t been put off by the comments and advice given in the previous posts, and I hope you realise that they are logical and good advice, a lot of planning is needed for an endeavour like this, and if you are to succeed then nothing should be overlooked, for instance some of the little things, like if you carried a mobile phone, how would you keep it charged up, a necessity in my opinion as should you need help then you need a means of contacting somebody.
There are many people who undertake a trek like this, by doing it in stages, and there is nothing wrong with that, may take a bit longer but it probably is a lot safer and a lot easier to achieve the goal.
So don't be disheartened, its a good Idea, plan it out, look for the downfalls you may encounter and plan to overcome them, read about other peoples adventures of a similar theme, pick up as much information as you can, don't rush into things, find out just how tough you are by doing week long stints, read up on foods you can forage at certain times of the year, and plan accordingly, learn about traps and baits to catch wildfowl etc,
( If you know all this please forgive my ignorance, but I was just trying to cover all the options, not knowing what experience you have etc, etc)