I will be in London for 3 months (Nov-Jan) and am looking for a private studio/flat. I've posted notices on Craigslist and Gumtree. Any other suggestions?
You need access to the rental ads in London newspapers.
Those are great and if you get results might be the best but when looking for accommodations this summer I found many rental agencies in London that do longer short term rentals for furnished flats. Most say that they don't charge VAT if you stay long term. Here is one I'm getting monthly newsletters from:
www.central-london-apartments.com/full-list.htm
and this might also be a good place:
http://london.sublet.com/
Check out www.dovercastlehostel.com and click on Flatshares on the left.
In addition to the hostel they run in Southwark, they own several flats that they rent out for short-term overseas workers, students, tourists, etc. staying for 6 weeks or longer. I think for a single it's £80 a week. The flats are in Zones 1 and 2 (Southbank). I believe they're private rooms with shared bath/kitchen, not sure if you're interested. But it's definitely cheap!