I wouldn't be surprised if that is true but Samsung have quite a few models for sale in the UK across many different price points so that pretty much covers the entire phone market.
I know the flagships don't sell out as quickly in comparison to the iPhone but that is only the top end of the market.
Lining up for any phone, Samsung, Apple or otherwise is dumb in my opinion. It's a phone, and in another month or two, everyone will have one and you will no longer be the cool guy with the GS5 or iPhone 6.
The only time I ever really considered getting in line early for anything was when Buffalo Wild Wings was giving out free wings for a year to the first 100 people in line for the grand re opening at my local franchise. Still didn't do it.