I have a signed and authenticated photograph of Laurel an Hardy in a
glass-fronted, gold-leafed frame. I am no fan and thus would be keen
to hand it on to someone who is. However, I'm also skint so I would
prefer to sell it for the best possible price (from my point of view).
Does anyone have an estimate of its worth? Also, where would I sell it
(I live in London, UK)

Give it a go on ebay.

You can always set a reserve & see what happens.

Good luck.

My thoughts exactly, Bryan!

You've got little to lose trying to sell it on Ebay with a reserve. I
second the idea!

Sincerely,
Boquinha-ga

You can't set an informed Reserve price on eBay if you don't have a
good sense of what your piece is worth.  There are highly respected
dealers of celebrity autographs in London -- one of the researchers
can post those.

In the meantime, you should check out  this site, which can help you
guage the quality and authenticity of what you've got.

http://www.laurelandhardy.pwp.blueyonder.co.uk/autographs.html