Why do you have to drive in the bus lane?

During your test you need to demonstrate your understanding of road signs and bus lanes are included in this just in the same way that you show understanding of speed limits by using the correct speed. Examiners want to see how you make the most of bus lanes and want to see that you understand how and when you can use them. Buses can be a pain stopping and starting but you can avoid this being a major problem by observing early when you know or think that the bus is going to stop and react early eg mirror and signal in advance to pull out again. These are good opportunities for the examiner to see how good you are at changing lanes too. You will benefit from learning these techniques and be glad to be used to performing them when you finally p your test.