Racks in London, UK

[Simon Hogg]

Can anyone recommend a cheapish rack supplier in London, UK, that I can buy 
a rack from for home.

Also, while we are on the subject, is a rack size a rack size, even for 
things like audio and scientific equipment.  I.e. is there a standard 
'rack' (I assume 19") with standard U / .5 U fixings.

I only ask that because I would like to rack up a whole bunch of stuff 
(music and computing) on the one rack.

Simon