I hate to break it to her but with the notable exception of defending the Falkland Islands, England pretty much is already irrelevant. Any such move now is a vote to save something from what’s left.
Their empire is gone, their colonies are gone (a fair few condemned to tribal poverty and violence in the absense of their Judeo-Christian rulers) their military might is a joke, their crime rates are through the stratosphere, their citizens have very few more rights than medieval times, and their nation is practically a Muslim outpost due to PC bullshittery on immigration and a collapsing native birthrate.
Also, the crime rates are not through the stratosphere and their nation is not a Moslem outpost yet.
While things are bad, your statement is hyperbole