Rear brakes are a 10 minute adjust per side and 20 mins gaffing with the adjuster under the center console to lock it back.

You just need to take one rear wheel bolt out and find the annoyingly small hole to get a Very long flatbalde screwdriver in to adjust the mechanism.

If you have the ability it makes it easier taking the wheel off. There are plenty of videos on YouTube. My e61 failed two years in a row and just needed maybe 2-4 clicks on each wheel to get it to pass. I did mine the car park outside the MOT station!

BMW handbrakes are renown for being s***e.

The first issue looks the more serious, I can’t help there without your MOT inspector telling you exactly what part is worn/broken. Hopefully it’s a cheap little arm that you might be able to get a pose to the whole unit clavion has put.

If it is the self levelling arm sensor then the only reason it would have to go to a dealers is for the suspension to be recalibrated. Any decent BMW indi will be able to do it for you. Or maybe something like a Foxwell scanner could help you if someone lives near by?

I know my NT530 does the single axle rear air suspension calibration and you can pump up each individual wheel To your desired ride height then you do the calibration.

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E53 3.0d Sport 119,000 Miles
E61 535d Estate - Hybrid turbos and Dark-side intercooler...389hp,792nm