Many thanks to everyone who has taken the time to reply - it's always nice to see how conversations really take off on posts like these!
To add a few thoughts of my own and explain why I posted on here rather than simply looking online for myself...
Seemingly all of the e-bike shops within reach of where I live seem to only stock mid motor models with a price range of £1600 and above. Oddly enough, one shop stocks front hub bikes, which I wouldn't fancy riding on the roads in question (or on any road with corners, for that matter).
I'm keen to avoid mid motors as I have a Kalkhoff Pro Connect i8. Ever since the Impulse 2.0 motor died it's basically just a big lump of junk that takes up a lot of space in the shed. I've read up on the possible problems with rear hub motors, but for the commute in question I think I'd have to do something really stupid for the motor to damage spokes (dodgy road surfaces are much more of a concern!).
For me the main advantage of rear hub motors seems to be that the bike can still be moved by pedalling even if the motor goes horrifically wrong. That's a major point in their favour given that the Impulse 2.0 died for the last time on an uphill slope 2 miles from home!
Another advantage of rear hub motors is that they're simpler to replace than mid motors (and much less expensive, too). Taking the Impulse as an example, now that it's been withdrawn (for extremely good reason!) it would make sense to fit a new mid motor but of course mid motor frames are designed for one specific motor. Plus the cost of replacing the old Impulse system with a new system would cost almost as much as buying a new conventional hybrid bike anyway!
The job in question is full-time sole gardener on an 11 acre site, so I can definitively say that the bike wouldn't be used for anything outside of getting from A to B! That's one of the main reasons I'm considering getting an e-bike for such a short commute - the hills aren't major, but after 8 hours of physical work the last thing I want to do is pedal uphill for half a mile! Plus the road after the jill is a bit of a wind tunnel, as well (south westerly direction in a part of the country with south westerly prevailing wind!). What energy I have on days off will be used for other things, such as working in my own garden or having a bloody good sit down.
Having said that, current top of my list is the Woosh Rambletta. It meets most of the specs on my wishlist and has the added benefit of folding down in case I do any work-related travel by public transport as part of my job (visiting plant nurseries, for example). It would also suit me if I don't get the job in question but do get a job requiring a bus ride for part of the commute.
That said - and as Woosh has mentioned - current problems with the supply chain might scupper any purchase in the near future...
But of course I haven't even heard back about my application for the job yet so no need to decide for a while - by which time hopefully Covid-19 will be much less of a threat and the Rambletta with updated specs will be available.
Thanks again!