where to buy MSG ?? help !

Hi,
So I've been getting into chinese cooking but many of the recipes I've
seen use MSG (mono sodium glutamate), availible from any supermarket my
book says.

I've looked in all my local supermarkets and today I went to a chinese
supermarket to look for this elusive ingredient. I looked through all
the spices, salts, flavouings etc. asked the shop assistants (who spoke
little english) but they just lookled at me like I was mad.

So does anyone know where I can get it ? what name is it sold under ?
what does it look like ? and where will I find it (salt section,
chilled goods etc)

Any help is much appreciated
Ta.

ps. i am in the UK