I'm afraid you've picked the wrong time to take up counting the cards in Blackjack.
I'm told that the LCI outlets in Town now offer only 8 deckers, and the other that springs to mind is the Palm Beach just off Piccadilly, near Green Park tube station - although I'm told it's a tad sweaty I've never played there myself. If you fancy travelling, the you might wish to consider paying a visit to Napoleon's in Sheffield, Hull or Leicester Square in London (they pride themselves on offering the best game in Town), or the Palace in Great Yarmouth where you can play your heart away from a quid a hand. When I visited a Gala last October, the six deckers had already been swapped out for those nasty one-to-six vacuum cleaners, and I'm told this has happened across the former Gala estate.
With regard to shoe dealt blackjack opportunities, I would say they've gone South big time since the Gala chain was taken over by the Rank Group and the outlets are to be (or have been) rebranded as Grosvenor.