The elusive ultra cheap night in London is still pretty elusive I fear. In central London your best bet are the hostels (go for the International Hostelling affiliated ones) http://www.yha.org.uk/sctn_rgnl/london.html

Once you start moving out of London - for e.g., to Kingston as in one of Sandy's recommendations - then prices fall, but you start paying more money for transport in.

Also check out Loot, THE small ads paper in London. I will not pretend it is common, but you may find a short-term flat share or flat sitting arrangement that works out cheap. http://www.loot.com. You could always place an ad.

From my experience, 35 quid is about as good as it gets in the areas you mention, unless you want to stay somewhere a little more interesting at night.

Jonathan

Jonathan Turton London/D�sseldorf http://www.travelinsights.org/