Heh, my boyfriend saw British Blues on a lifestyle show and keeps going on about them (because they're supposed to be really placid, and my kitten is a maniac!).
I don't really like any of your choices -
Bailey,
Charlie and Jazza are all too trendy and bouncy,
Matilda and
Gabriela don't sound like cats, and Pola doesn't appeal.
What about:
Dulcie (really liking this)
ConnieLucyBonnieBess (really liking this too)
PoppyMistyDustyTibby (sorry to our poster
Tibby, but it works!)
MillieTillieBobbieChloe
I definitely feel that a British Blue ought to have a very British-sounding name, and right now the trend in England seems to be nicknamey names ending in 'ee' sounds.
Let me know if any of those appeal or feel like the right style for you.