I live in a large town on the edge of London, but sadly no dept stores here. Luckily, Central London is only 20 mins by fast train, but I completely agree with @AprilLady I get easily overwhelmed when smelling scents in huge fragrance depts a la Selfridges, JL, Harvey Nicks, Liberty etc, and find I don't really get a good, detailed impression of them.
I tend to try and pick just one or two scents to try instore (VERY hard), usually beforehand if I know the store well, spray a card or myself, then immediately leave the fragrance dept. I usually get to know if I like it from that, and if it's worth a 1 or 2ml sample. If I'm tempted to buy a FB, then I definitely try and get a sample first.
I do miss all our dept stores though, as I loved browsing all the different depts each season, esp at Christmas, then going to the upstairs restaurant/coffee shop. I still find dept stores comforting, and could while away hours in a really good one.
SOTD was a spray of Chypre Sublime, courtesy of my mum, who sprayed me from her bottle. I'd forgotten how long this lasts, but how I wish the patchouli was more prominent and rich, to balance the really quite strong rose.
SOTN is Shalimar, I keep saying it, but it's absolutely freezing! ❄️ So beautiful in the sun though - all spring-y and cheerful, esp looking at the hyacinths and daffodils blooming in the park. I'm feeling quite Easter-y! 🐣🌷