By way of update, after doing said research and having a good hard think about what I actually wanted out of my future bike, I realised that I didn't actually need an e-bike at all. What I needed was a decent all-round ordinary bike, and then to get off my rotund backside and do some work. To that end, I've ended up with a Trek Dual Sport 3 (Women's) which I picked up last week. I've only been able to go out twice so far, and only managed to stay out for just over half an hour each time and then spent the rest of the day feeling rather sore, but nevertheless, I'm pleased to report that it's been a lot more fun than I remember biking being, and I'm looking forward to going out again next time (and hoping that the ratio of time spent on bike to time spent feeling sore afterwards will soon begin to adjust in my favour!).
So, in sum, thank you all for helping me come to what was ultimately the right decision, even though it wasn't on the cards at the beginning of this thread!
