Needless to say this cunning plan fell apart. Portobello Road was there but the market wasn't, and the post office closes at one on Thursdays. Never mind, I got to walk around those streets without having to fight my way through crowds for a change - and I suspect that it's actually an OK place to live if you don't mind the Friday and Saturday crush and the noise of the carnival once a year - hit the book shop at Notting Hill Gate and found some comics I wanted (including an issue of Top Ten I could have sworn I'd bought but can't remember at all), and went to the Queensway post office which is open all day. And I got a little exercise, which is good. And tomorrow I can do it all again with added crowds and actually get the fruit and veg I went for today...
Later: Forgot to mention the charity shop bargain of the day, which was the three DVD Spaced series 1 and 2 "collector's" edition. For 6 quid!