Thanks guys. I think I've found what I want - overnight a company that I have purchased t-shirts from before (I wanted some that were long in the body as I'm 6' tall) sent me their latest marketing newsletter
http://www.polo-shirts.co.uk/ when I clicked on it I saw they have a sister company that do printing
http://www.clothes2order.com/ps_landing.php and they do single shirts.
If anyone is looking for heavy weight and "tall" then Gildan on their shop is the one to go for. I got a batch of them just for general use and was very pleased.
Now that I know they do "one off" shirts that'll do me.
I'll bear in mind the embroidered site. On this occasion it is just for a joke (really one t-shirt) but I don't want to buy rubbish as I'll still wear it after the joke is done.