The clouds rolled in but not all is lost.

[Danjc]

So I managed 3 x 300s subs on M81 and the clouds stopped play and my plan has now been on pause for an hour and a half !

However I have sorted my guiding out, ran with my new Pegasus Astro PPB, tried dithering for the first time and also used Remote Desktop to my phone. 

I reckon another 45 ish minutes of waiting to see if the poxy clouds do one and if not a tiptoe round the garden playing the trying to not make any noise game. 

[StuartJPP]

It's all part of the experience I'm afraid but as you noted it is not wasted time.