I actually stopped going to physio.
Their advice was to constantly do x,y and z stretches as well as massaging the arm daily.
I never did any of those things for more than a few weeks and all it caused was pain.
On the other hand ignoring what they said and doing weight training gave me far better ROM after just a few months and now it's back to 'normal' with no pain unless it's cold.
The cold snap we've had recently hasn't been great.
I'm in Devon so I guess I've got similar weather to you at the moment.