<<Disclaimer: Verify this information before applying it to your situation.>>

I don't know the GF status of the following milks but you would be able
to check once you were in the shop or look at the website below. If it's
of no help, feel free to use that delete key!

You can buy rice/soya/oat/goats/sheeps milk  in a variety of health food
shops such as Holland & Barret, Health & Diet Centre plus independent
ones, around London.   Some soya brands are Provamel, So Good.  Other
info is on the UK website No Cow's milk for me at
http://dialspace.dial.pipex.com/town/park/gfm11/

Also supermarkets such as Asda, Sainsburys and Tesco sell the soya milk,
haven't found rice milk there as yet but it seems to depend on the
individual store you are in.

Boots do not sell any alternative milk at all. Not sure about Marks and
Spencers. It is more a gourmet food court in there.

Happy travels!
Steph