The bigger department stores often have them... if they think you are a serious customer and are undecided about a couple they may have phials to take away to try over a few days. they don't often give them out as they tend to put them in goody bags to give to customers who spend quite a bit
House of fraser are great. I went in for some samples and walked out with a full makeover of all their expenses brands without paying a penny. But maybe they thought they were doing the rest of the shoppers a service by sorting me out :)