To answer your last question first, there's really no such thing as being a "Brit" here. We think of ourselves as "English", "Scottish", "Welsh", "Irish". Never British, though our passports say "British". The only time we ever hear the word is from Americans. ;)
Regarding green tea strength, the overwhelming majority of Brits (sic) just drink whatever the supermarkets sell, as you'd expect. That's, almost without exclusion, low-grade tea in bags. The flavour and aroma of these things is beyond mundane, and the concept of "strength" isn't really applicable to the way the average person here drinks green. Not that very many people drink even that "green", of course. The vast majority drink assam/ceylon blends. The rare few might take whatever mediocre offerings are available from Twinings or Whittards.
In the last few years, a horrific trend towards drinking "herbal teas" has come about. These are mostly flavoured bags of rosehips, lemon, ginger, &c., often made by Twinings or their ilk, and are called inspiring names such as "Strawberry Soother".
I visited an undergrad friend of mine recently. She said, "Ooh yes, I'm MAD about tea! I collect it, in fact!" She proudly showed me box after box of Twinings herbal teabags. I sniffed back the tears.
Toodlepip,
Hobbes