On the last day we finished a bit early (they always pad these things, in case the instructor is saddled with a room full of dribbling morons) and seeing that it was convenient I popped in to the Bank of England museum. It's very small, only takes about an hour to go round it all, entrance is free. It gets the Evil Dave Seal Of Approval as being an excellent museum. Both Londoners and Foreigners should go there.
On the way out I raided their shop and bought some Bank of England chocolate. It's a pity they don't sell monopoly money and poker chips too!