Pardon the Christmas name change, it's really MissConductUS.
I've decided that I am going to treat myself to one of these watches. I decided to go with the series 4, just GPS, space gray with a sports band. I concluded that for me, the series 4 was worth the extra money, mostly based on this review
Apple Watch series 4 battery test in fitness tracking
which said that when hiking and running the 4 was much easier to read due to the larger screen and that the battery lasted much longer. She wore a series 4 on one wrist and a series 3 on her other wrist for a six hour hike and run.
This review was very helpful too.
www.cnet.com/reviews/apple-watch-series-4-review/
The price difference is a bit less here in the US because you pay the same number of GBP's as we pay in USD and the dollar is worth less.
So I've ordered it from the apple website for pickup at my nearest Apple store, which is in a very posh shopping mall about 20 miles away. I'll go and pick it up at 9:00 when they open. DH thinks I've lost my mind to go anywhere near that mall, which will be mobbed with people Christmas shopping. Hopefully I'll survive. 
Thanks to all who shared their personal experiences with the watch. DH and I really just do practical presents for each other, so it will be nice to have something fun for myself this year.