They have a free collection service. They hung a little flyer on wheelie bins before Xmas giving details of holiday collections and dome details about tree collection. Threw mine away but someone on here might still have one.
The Christmas trees are going t0 be on the streets for another week or so: the collection services starts on 11 Jan:
From
http://www.lambeth.gov.uk/Services/Environment/RubbishWasteRecycling/GardenWaste.htm
Christmas tree recycling
Each year we run a Christmas tree recycling scheme at the beginning of January. Depending on the type of property you live in, we will either collect your real Christmas tree from your home or from a local drop site.
If you live in a kerbside property, leave your real Christmas tree next to your refuse bin on your normal collection day. If you live in a Lambeth Living property, leave your tree next to your estate recycling bin. We will pick up the trees in the week commencing 11 January 2010.
If you do not live in a kerbside or Lambeth Living property, you can still recycle your Christmas tree by taking them to any of the following drop sites:
* Clapham Common, Windmill Drive, SW4
* Kennington Park, Kennington Park Road, SE11
* Streatham Common, Streatham High Road, SW16
* Lambeth Reuse and Recycling Centre, Vale Street, West Norwood, SE27
Real Christmas trees are being accepted at these sites from 11 – 15 January 2010.