So moving on from my previous thread about where I should go, I've decided to do the West Country Way from Plymouth to Minehead in August. Which leads me onto my next question- tyre choice. I'm currently running 700 x 40mm Hutchinson Touaregs. Butbim wondering if there is a better choice in the 40-42mm range as the Touaregs aren't the best for anything that might be the tiniest bit sludgy. So does anyone have a better suggestion? I'm currently looking at pirelli cinturato m and wtb nanos,but open to other suggestions.

I'm running Pirelli Cinturato M, in 700cx45mm flavour and they've been mostly excellent. Puncture resistance has been good and when they have punctured, the Orange Endurance has sealed them up without any extra help. They're big enough that you can run low enough pressure, so you're not spending all your time wishing you have biggerer tyres on. Like most gravel tyres though, I've found them proper sketchy when it's pissing it down and the ground it getting squelchy and sloppy; but then they're a mixed surface tyre, not a wet weather tyre.

you can either have a decent fast rolling tyre that is ok in most scenarios or a tolerable mud tyre that is a lot slower

IME even my mud CX tyres [ 35mm] were not that great, in mud, as its hardly a Maxxis Shorty. Skinny tyres will never be that grippy - i use 1.8 mud X on a 26 er and they are still slippy IME as they " cut" through the mud
I use teravail Cannonballs[ 44mm] on the cross bike which are a doddle to set up tubeless and have yet to fail me

Was riding at the weekend with a mate using Cinturato M 50mm. I was on Vittoria Terreno Dry 47mm. I rolled a lot quicker than him on offroad descents, whatever the surface, but pretty much the same on tarmac (no, I know that doesn't make sense). On a slippery climb (grass and a bit of mud) I followed him up and watched his tyres slipping a bit where mine didn't.
Conclusion, I'm not sure they had any better grip than my faster tyres, but rolled slower.