Inevitably that is all headchecks are while you are a learner. Until you're driving by yourself and almost get in an accident with some dickhead in your blind-spot, then you start knowing what to look for and actually LOOKING when you change lanes (and staying out of other people's blind spots).
Ahaha, he's the dickhead because you nearly ran into him?
Just use your rear view mirror aggressively and gauge where the other cars are at all times. So if they're creeping up on you, realise that you need to check them again. Just takes practice
Hahhaa, yes, he is. For sitting in my blindspot.

After a bit of experience, you start being aware of your surroundings. Ideally, you should know where other cars are, their speed and where they're going to be, if anyone is in your blindspot, and as a precaution if you are in anyone else's blindspot (saved me from accidents so many times).
Also, for changing lanes, if you can see their headlights in your rearview, there is plenty of space for you to get in.