No real need for nerves - just do what you've already been doing... The skills test is just a final check by an independent third party (the examiner) that you're doing things safely and competently, such that you can continue to do it in future without the oversight of an instructor each time.
The thing I was told to bear in mind about the skills test was as follows:
By the time you do your skills test you are already a safe and competent pilot. You have demonstrated that you can plan, fly and navigate, and if things go wrong you can sort it all out and get back on the ground. If that was not the case, they wouldn't let you take off solo in an aeroplane and fly around the circuit or do a solo cross cross country.
Sure you can muck it up - but there's no unexpected gotchas, just do what you've already been doing both with an instructor and on your own (solo).