I am 53 though look a lot younger according to my friends
I buy from
Boden
Kew
Jigsaw
Monsoon ( a little)
Next ( a little)
If you are slightly conservative you should look at Kaliko, Hobbs, Next, M&S Autograph.
Most of the above all do mail order.
Keep away from the 1st floor of all dept stores- unless you are going to Selfridges or Harvey Nics- as they will all date you- especially country casuals and the like.