Re: wildflowers, although I love the idea, are they not annuals? I could incorporate them somehow though... Some are annuals, which are the ones that like bare places, because going through their whole life cycle in one year doesn’t leave them energy to be tough and compete with other plants. More, incuding most hay meadow plants, are perennial.
I disagree that returfing would be the easy option, that would require more maintenance than growing something that was happier there.
For me, plants which change with the seasons are what make gardens interesting, so while I’d have the odd evergreen, I wouldn’t make it all or mainly evergreen. Winter interest can also be obtained by coloured bark, berries, and things that flower in the winter.
Do you use that grass? If not, I’d plant up the whole of the front, less maintenance, and not time critical - you don’t have to mow it every week.
do you think if I put some lawn edging in and keep the flatter bit on the left as lawn for now, that would look ok? I was going to suggest lawn edging, to provide a distinction between the grass in the lawn and the grasses you have in the flower bed. You want them to look intentional, not as if they’ve strayed from the lawn