Which bike? With a twist... I'd like some female input ideally!

My mother bought herself a bike with hub gears last year - a Felt hybrid which is not totally sit-up-and-beg, but fairly close. It's nice and light, and when I borrowed it I was just about able to keep up with my sister (on a road bike) but the gearing doesn't meet my mother's needs all that well. The Shimano nexus hub is one of the three speed ones, and my mother would really need the seven or eight speed version to even out the mismatch between the power she can produce and the hill she lives on.

Decathlon are probably worth a look too

I don't have one (I have a road bike only) but if I was going to get a city bike for around £400 I'd probably go for a Bobbin bicycle. Lots of colours, styles, easy to maintain and kind of 'vintage' styled. Most have hub gears and there are loop, mixte and step-through type frames e.g.

http://www.bobbinbikes.co.uk/bobbin-birdie-sky-blue/

I have a Giant Expression DX, bought it after my youngest sons were born. I've never had a ladies bike before, but needed something I could get off & on of easily & able to tow a trailer.
It's almost 8yrs old now & still going strong, it's towed upto 9stone of child & trailer, fully loaded panniers over the South Downs. The only thing to need fixing has been a few rear spokes & 2 new chains.
I'm back on a road bike now, but i'm keeping her in the shed for my 'old age'

Have you looked at the Raleigh range. My cousin bought something similar to what you have described, and she has been happy with it.