Road bike recommendations

Hey all,

My girlfriend is interested in doing the Dunwich Dynamo this year after my tales of all it's varied joys... She's after a bike that fits as she's previously only ridden my bikes (56 cm frames with a 110mm stem) which are too long in the reach for her. She's about 5.10, so quite tall.

She likes steel bikes, but budget isn't huge (still TBC but likely absolute max of about £700) so it largely puts OTP steel out of reach. Having spoken to a couple of people it seems that women's bikes might be a better shout than a second hand men's or "unisex" frame- something about longer seat tube but a shorter reach. Is this true?

I don't really want to use a really short stem on a man's bike as I want her to be confident and the bike can't be twitchy (first road bike).

I was kind of thinking of looking for a used steel frame and putting new tiagra on it or something. I have some wheels that she can use (racing 7 LG).

Any thoughts on sizing for women's frames generally? Will do that competitive cyclist online fitting thing at some point too.

Cheers