Given that the weight is listed as 10 oz for size small, I'd might be inclined to go for something a little lighter; in fact, for my next long hike I just ordered an Outdoor Research Helium Jacket. Lower hydrostatic head and have to reapply the DWR periodically, I reckon I'll do that via mail at a couple of gear swap times (mail Nikwax back and forth). And I don't think it covers the hips as well. But it weighs 6.8 oz in size large.
For where you're going, the thru-hiker jacket might be a very good choice, especially on sale, and especially if you're disinclined to wear rain pants, chaps, or skirt (I'll be using a Zpacks cuben rain skirt). My wife and I walked the Wainwright trail in September, and my poncho (actually Gatewood Cape) worked okay overall, but there were a couple of times on the moors where the wind was fierce enough that I reckoned I was better off without the cape flapping about --- that's very much "not normal" for where I generally hike.
Another factor about hiking in England --- are you mostly camping, or are you staying in hostels and B&B's and the like? We did the latter (a stipulation by my spouse). In that case, I think it just matters a whole lot less that you get the absolute optimal piece of gear. You would be carrying less weight (no tent, sleeping bag ...), and have a chance to dry everything out every night.