My choice:

 

Werewolves (of London)

 

It would even come with a chant/cheer/howl.

Royals - everything is about royalty there

Do they play their national anthem before games there?

The London Kings

 

The London Rippers

 

The London Blitz

Monarchs

Redcoats

Plague (probably not)

Jet-lagged

I'll second the werewolves.

Do they play their national anthem before games there?

They did Sunday.

The bridges or the Beetles (spelled wrong intentially so they could have a mascot)

The Nil-Nils.

an away game

The London Fog

My choice:

 

Werewolves (of London)

 

It would even come with a chant/cheer/howl.

 

I'll second the werewolves.

 

Same here.

 

The London Fog

 

But I like this one too.

Weren't they the Monarchs in the World League of American Football? I wonder if they'd try and re-brand that.

Do they play their national anthem before games there?

 

Having sat with a couple Brits at a few sporting events, they're very puzzled by the practice of playing the anthem before a game that doesn't involve a national team playing in international competition.