Back to the OP
1. Reporting to the police? It depends on the police force, and it depends on the local officers, but .... probably not worth the effort.
I used to have a contact in W Yorks who would respond to such a close pass; he's now retired.
Now - well, a close pass doesn't really stir them very much.
[Edited to add] Sorry, I missed the reference to the MOT. Sad (but true) - that may be enough to prompt police action.[/edit]
2. Reporting to the employer? Worth doing?
You may get any sort of response, from
(mostly)
- blank silence; or
- a brush-off letter/e-mail;
to (
rare gems 
)
- "we employ cyclists, and I am genuinely shocked that one of our drivers should show such disregard for their safety .... etc" (one unhappy boss!
);
- "my wife is a keen cyclist, and races with our local club; I fully understand your concern .... etc" (one REALLY unhappy boss!
);
and everything in between.
Best of all (
but even more rarely!)
- being invited in for a meeting with a senior manager, and be asked what you think they could do to raise standards (
I wasn't expecting THAT one, but suggested they get in touch with the council's bikeability trainers for some cycle awareness training - which apparently the company followed up on!);
- another meeting with an NHS transport manager, who was very genuinely shocked to realise the driver training he was responsible for was based on cycling standards of the 70's, and just how much ideas on things like road positioning have changed. I left the meeting, and he was all fired up to revise the training programme and make changes;
- and a local taxi operator who realised that my CD with 24 videos of his drivers behaving shockingly towards a cyclist, over just 3 months, meant rather more than a rap on the knuckles for the odd driver from the council licensing office. His operators' licence was in jeopardy. His taxis are now "princes of the road".
but like you i say whats on my mind and its not always understood in the way its meant 
