Treat it with the same attention to detail that you have applied in your lessons. The other posters are quite right - relax and enjoy. You will probably find that your examiner will make helpful suggestions and that you will find it a very useful experience.
Afterwards? Ah well.....many drift away unfortunately because, without the 'organisation' of your lessons, you have to make your own routine and it is easy to find that you have exceeded the 28 day club rule and will need a checkout. A good idea is to plan to go places - visit other clubs - fly in different airspace e.g. MATZs and your experience will grow and grow. Many clubs organise flyouts, so join some of those and gain the experience of others.
I wish you good luck and I hope you enjoy the flight.