In case there is a difference, I used the term 'agent' although we really know them here as 'brokers'.
There is a difference here. An agent would be an individual (in the old days a door to door salesman) representing one or maybe a couple of companies. They seem to have pretty much disappeared here.
A broker is a company licensed to place an insurable event 'on risk' before you take out a full policy for example.
The broker also handles everything for you (or does if its a good one). You make your claims through them, they advise what you can and cant claim, what claims might affect future premiums etc. Ive used the same broker for 15 years now as they have an office in the village, and Ive known the manager since he opened that office.

Here is something I am curious over as I heard conflicting stories before.

Lets say you are going out to buy your first car (so you have no motor insurance). You pick out a car at the dealership and its ready to drive away. How does the insurance work?