Different junctions have their own unique features which means your observation and behaviour need to be alert to the different hazards that could present themselves. Typically, these fall under 3 main skills; turning left, turning right and emerging.
Turning left is most likely the first manoeuvre your instructor will teach you when dealing with junctions. That's because it only requires you, as the driver, to deal with 1 direction of priority traffic.
You won't need to worry about traffic moving from left to right ahead of you, only the right to left traffic that you will be joining. Of course, you will need to be aware of other potential hazards, such as cyclists appearing on your left.
How to Practice:
Once your instructor has introduced you to left turns, you can go out and practice in your own time. Be sure to either only go a route where left turns alone get you to your destination (or swap with whomever you're with once you run out of left turns) or go to a retail park car park or similar where you can essentially turn left forever.
If you haven't done right turns with your instructor, be sure to let the person you are with know. Right turns are a different skill and you shouldn't be forced in to performing skills you've yet to learn.
Turning right is a surprisingly more advanced manoeuvre than turning left, as the flow of traffic from both directions gives you a lot more to pay attention to, calculate and respond to. Think of a T junction where traffic coming both ways has priority over you. Take extra time and care.
How to Practice:
Only once your instructor has introduced right turns should you go out and practice privately. Shopping centre car parks are a good introduction to practice in a controlled space. Otherwise, residential streets will require both right and left turns in abundance.
Emerging into traffic is assessed additionally as part of your skills at a junction. Performing all your safety checks and being well-prepared to join the flow of traffic is one part, emerging and joining the correct road is the next part of the whole.
Junctions To Look Out For
A 'T' junction, sometimes called a "3-way junction", is a typical road layout where you usually have a minor road connecting to larger road. You need to be aware of who has priority and right of way.
A crossroads, or "4-way junction", is where two roads cross over each other. Road markings or traffic lights will inform you of priority. These roads may feel quite daunting, but study some illustrated examples or ask your instructor to draw out some situations you can study and you'll find you have all the knowledge required to assess the situation already.
More common in residential areas or out in the country-side on smaller lanes, roads without any markings do not give you any feedback to get a sense of priority. The surprising thing to note is that, in truth, no-one has priority. It's up to the driver to use their best judgement.
Often, these are in areas where cars won't be travelling at speed, but use your same hazard perception techniques to make sure the situation is safe and travel on at your discretion.
Junctions With Yellow Box Markings On The Road
Busy junctions may have roads marked with a yellow box with cross hatching lines within it. These indicate that you should not enter the junction until your exit is clear.
In practical terms, these yellow boxes are communicating that if you were to move forward and stop in the box, you have a high chance of blocking other traffic. By sitting back, outside the box, you are allowing other traffic to flow. Once your exit becomes clear, moving in to the box and out of it to your exit in one smooth movement is the correct behaviour.