I thought my instructing day had finished, but always up for another lesson.
Roundabouts:
This is information overload. It affects the best of us at times - just listen to some ATC conversations on youtube where professional pilots are struggling to process information because they are dealing with mechanical failures etc.
What you need is strategies in place to deal with the information flow. You will be trying to think of everything at once and as a result think of nothing.
The most important thing is as soon as you get an instruction, check mirrors and reduce the gas. And this next bit is crucial - you don't need to be able to see the roundabout or understand where you will be going to do this - learners who are struggling with this generally try and wait until they fully understand the scene before they act and you don't have the time to.
You need to be aware of surroundings prior to slowing, but the sooner you begin to slow the better - what will almost certainly be happening is that you are not slowing in time (for your ability to process things) and then you get overloaded. Getting off the gas early is the first step to making the time you need. Don't be afraid to start braking early and gently either - this gives you more time and helps to control the cars behind you.
Parking
Don't think just do my young apprentice...
I get really fed up with instructors who are wedded to using reference points for manoeuvres. They should be a weapon of last resort, a final tool in the toolbox for when all else fails, not the first thing you turn to.
You have eloquently summed up a big chunk of the problem with them - "I can't remember the sequence". Up until about 25 years ago people didn't normally use a sequence of events to reverse - they just reversed. You are spending all your mentally energy trying to remember a recipe rather than learning how to cook.
Where am I? Where do I want to get to? Move slowly and steer - is that doing what I want, not enough, too much? Add more steering, reduce the steering, steer the other way. Rinse and repeat.
Routes
Why are you trying to remember routes? Is it something you've been told to do?
The whole point of independent driving on the test is to follow the satnav or road signs, not to remember a route.
You are already struggling with information overload, don't try and add to it by remembering routes.
If you are following signs, scan for the place you are interested in and if it isn't on the sign, move on. No point wondering why the road you are on goes to Dunny-on-the-Wold if you are supposed to be trying to find Craphouse-on-the-Widdle.