I hate to break it to you, but "Sally" here looks like a male. The bulbs on the ends of the palps are a dead giveaway. Male spiders are normally smaller than females, but not necessarily slimmer, especially if they are well-fed. I've seen spiders become visibly fatter after a large meal.
The lighting in these pictures is such that I can't positively identify the species, but it looks almost identical to the orb weavers that I usually have all over the outside of my house this time of year (they are strangely absent this season). Considering that we live on opposite sides of the pond, it is most likely a different species in the same genus (Araneus).
Wow you know your spiders!!
At least I'm not foolishly waiting around for baby spiders now 🙃 Thanks