Hi Nigel

I live in Cumbria and heres what I reckon…
Swinside/Sunkenkirk is at least an hours drive from M6 J36.
Swinside to Langdale maybe 40 mins.
Langdale to Castlerigg 30 mins.
Castlerigg to Penrith J40 25 mins.
I drive fast when I can so add a bit for a more relaxed pace and add a bit more if you're traveling at weekends or in the rush hour (yes there is one on the A590 – its horrendous)
It would be a great shame not to fit Long Meg in (about 20 mins from J40) although its not so wow in a mountainous way, it is very wow in itself and the sky there is just enormous. I watched the sunset up there tonight and it rolled down behind Great Mell Fell in a particularly delicious way.
Mayburgh is also wow in itself –and only 5 mins from J40.
Gamelands is stunning in a more gentle way and only 10 mins from J38.
Castlerigg is likely to be very busy unless you go just after sunset or its raining alot.

Enjoy your day (but just think how much more you could see if you made it two days !)
Claire x