Q:

Information about the office of the Chief Rabbi of England

Who determines the Chief Rabbi of England?

Is he picked by a general vote of all Shul attendees in Great Brittan?
Is he picked by a committee picked by boards of different Shuls?

What are his powers?
Does he have a monopoly on Kashrus/Weddings/Divorces (Like in Israel)?

A:

This article explains how the chief Rabbi is chosen and what are his powers.

Broadly speaking, the job combines two different roles. One is
  ambassador of Judaism to the outside world; the other is "rabbi of
  rabbis", the senior rabbi of the United Synagogue and other central
  Orthodox communities. While the roles are not mutually exclusive, the
  question is which will be given greater emphasis.
In theory, constitutionally, the chief rabbi is the supreme authority
  of the United Synagogue, and the Beth Din is there to advise him. In
  practice, it is the Beth Din that has been seen increasingly to call
  the religious shots, and the current Chief Rabbi has been accused of
  yielding too much ground to it.
His preference was to appoint a small working group of around seven
  people who would draw up a shortlist and interview the candidates.
  Their recommendation would be then submitted for approval to a larger
  representative group of around 30, made up of delegates from various
  constituencies under the aegis of the chief rabbi, but also possibly
  from outside. Mr Pack proposes to chair both groups himself.
When Lord Sacks was appointed, the decision was taken by a body known
  as the Chief Rabbinate Council, composed of around 200 members
  although a smaller selection committee of 35 was set up to recommend a
  name.
The council was superseded in 2002 by the much smaller Chief Rabbinate
  Trust, comprising three United Synagogue officers, three other
  trustees nominated by the United Synagogue and three trustees
  representing regional and other communities.

