There are many reasons for driving test anxiety, including:
Peer pressure — friends who have already passed and relatives who say unhelpful things like "I passed my driving test first time after only five lessons".
Comparing yourself to others is a recipe for disaster. Everyone is different and learns to drive in their own way and in their own time, what other people did is completely irrelevant to you.
Fear of failure — no-one is perfect. No one gets it right first time, every time. When they start to learn to walk, babies fall over, when toddlers learn to ride a bike, they fall off. There may be tears and hurt but mistakes and failures are good sometimes because we learn from them and driving tests are essentially no different.
Self-doubts and lack of confidence in your driving ability — if you've taken driving lessons from a professional driving instructor, and if your driving instructor is letting you use their car to take your test in, then trust me, they wouldn't be letting you do that if they didn't know that you can drive independently to the standard required for the practical driving test.
Your driving instructor believes in you so you should therefore trust their professional judgment and have faith in your own abilities as a competent driver.
Knowing in your heart that you're not really ready to take your driving test — this one is a bit different from the previous items in this list and it's one that you can easily do something about if it concerns you.
There are very few people in this world who are "natural" drivers. Driving is a skill requiring many different simultaneous mental and physical processes, which don't necessarily come naturally and which require learning in the first place and then honing by means of consolidation and practice.
If you have a test booked and you do not feel confident about every aspect of what you may be required to demonstrate, then my advice is do not take the test without further training.
Previous test fails — having failed a test previously adds a lot of extra pressure.
It's important to remember that the overall national driving test pass rate is only around 45 per cent so statistically more people fail the driving test than pass it.