I have spoken to the people that do these test and they say that if you email them stating that you are interested in there products and would like to test their products they will send you the nessassary paper work.
adress is mccormick.consumerpanel@mccormick.co.uk
The last one i did was for comparison of two types of gravies ( I didn't like either sample) but they sent a £4 voucher and hopefully I due another one mid January. They say not to apply until after Christmas as the lady i/c is on holiday and her name is Jacqui Leach.