However once I got to the garage I thought Just get out there Mark, be a man! So went for a ride thgrough Caterham, Chaldon, Bletchingley, Nutfield, Blindley heath and back through Godstone to Caterham. So nice sweeping fast downhills and what seemed like many leg burning climbs.
The rain was cold stinging and relentlessly pounded against my face. The driving head and cross winds vicious and the potholes deep. Cold hands and Wet from head to toe. Is this really fun.
Oh yes 
Front light packed in, it wasn't designed to withstand these conditions, rear light intermittent. Am I going to make it home before dark
Up Tupwood lane and through the viewspot in Caterham / Chaldon when bugger front punture. Hands too cold to get the tyre back on so warmed them between my legs for a while.
Finally got home just over two hours and over 25 miles.
It felt great. Not to be home but to have gone out.
So when faced with the same dilemma again, rain or turbo, it will definately be rain. It's much better than sitting in doors regardless of the weather outside.
It's great to cycle me thinks
Although if I was outside and it started raining I would usually stick it out. I'm sure I've been to all those places you've mentioned but not solo it would've been following some one else wheels. I can show you a very exciting training loop in central london 
