Out of interest, what were you even doing on the M3? M25 - M4 - M5 is a faster route.
It's a lot longer to go M25, M4 & M5.
From Woking, out via Chobham to Lightwater, M3, A303 all the way to Illminster, A358 to Taunton.
Simple, easy and the A303 is all dual carriageway (70mph) apart from some relatively small sections (60 & 50mph) of single carriageway namely from near Stonehenge to the other side of Winterborne Stoke, Wylye to Chilmark, Chicklade to Mere, Sparkford Hill to Podimore, South Petherton to Illminster (Now that bypass
IS DANGEROUS & was designed by idiots!). Also since I moved here I've learned loads of short cuts and I can get round the bottlenecks and trouble spots too.
Besides I usually go off peak anyway so the traffic is a lot lighter, so I can get a real good run home.
Oh stut, when you get your head out of your backside & realise that by concentrating on a speedo you're chances of hitting something or someone increase at an exponential rate, similar to mobile phone usage, let me know.
I suspect that you're one of the idiot drivers who hogs the middle & outside lanes and won't do anymore than the limit & will hold up everyone else in the process! Personally I'll just go around you! Yes, undertake! No, it's not illegal to do so provided that the manoeuvre can be achieved safely. Done it loads of times & it's legal otherwise you could find that everything will grind to a rapid halt on motorways etc where the inside lane (lane 1) will move first before the other lanes (2, 3 & 4).