The V&A is just over the road from the Science and History museums, and also has free entry. The courtyard in it is a great place to eat a picnic lunch if the weather's nice 8) The Science and History museums are good, but very busy. There was a huge queue for the main entrance of the History museum when I went the other week, but there's a side entrance on Exhibition road that was much quieter I personally prefer the Science Museum though - there are lots of interactive things to do, and not just in the 'Launch Pad' kid's bit