Unfortunately you will miss the Caravaggio exhibition at the National Gallery, which finishes on Sunday. Try the National Portrait Gallery at St Martins Place, London WC2H 0HE open from 10:00. Always tremendous pictures by great artists. Best Clive
If modern is your thing ... Robert Rauchennberg on right now ... and if you are gonna be in that neck of the woods, worth checking out white cube which has anselm kiefer exhibit albeit small these days.
If you in market to buy, there is London art fair in Islington design centre later this months which is pretty good with wide range.
Tate modern is fantastic. London's a great art town. Realize I'm late to all this. For older paintings and less hectic experience Coutauld gallery is fantastic. Damien Hirst's exhibition space is also cool, Newport street gallery. [nt]