Hi Rich,
As airpolice mentioned, one of the best things you could do is prefix your registration with "student", so that any ATC you speak to will go easy on you. I didn't and the controller at Cambridge got really sarcastic I wanted to get out and pummel his head in.
Also when planning your route, one thing that could make things a lot easier for you is planning your legs so that there are a lot of features en route - lakes, motorways, towns etc. will all help your dead reckoning and timing.
Bear in mind though that feature-crawling is something that your examiner won't want to see in the exam and that you're keeping a good watch on your leg timing and making corrections to your heading due to wind variation.
My instructor gave me my route (Elstree - Cambridge - Wellesbourne - Elstree), I wasn't told to plan my own. After having the worst time at Cambridge with ATC, the people at Wellesbourne were brilliant. Maybe the smaller aerodromes will make your approaches easier as they are generally more friendly?
Relax and have fun, it really is a great experience and you finish the long flight with a great sense of achievement!
Good luck!
