A 28 or 32mm tyre won't be too scary
Something like the giant linked above by MikeW would certainly be a good option or the Alight
http://www.giant-bicycles.com/en-gb/bikes/model/alight.1/19207/77383/
(outdoortraders sell Giant)
Perhaps disk brakes might be helpful if riding in the rain too (although they add a little bit of weight to the bike)
So something like the Whyte Carnaby (I have a Cambridge and although it's too small for me, it's really good to ride, comfortable and swift). Behindbars (excellent name

) sell Whyte
This colour is lovely, comes in a 'bone' colour too
http://www.pedalscyclecentre.co.uk/m1b90s382p6192/Whyte-Carnaby-2016/RS_GB/20531
A little over budget at £550 but most LBS's will negotiate on price
A carbon fork for reducing the weight a bit and also increasing comfort by reducing road vibrations is also my personal preference (but this will add too much to the cost if you want disk brakes)