London to Cornwall tomorrow morning, M4-M5 or M3-A303? Any thoughts?

[HeadAndShouldersPerson]

I've always gone M4-M5 but aa and rac route planner suggest M3-A303 is quicker by 15 mins.
I normally prefer motorways.
Leaving at 7am.

From Egham or thereabouts, I'd do M3, pick up the A303, then M5, then A30/A38 depending on where you are going. I have done Dover to the Devon/Cornwall borders with monotonous regularity for the past 13 years when we lived in Brussels; and prior to that, Cornwall to Hants v regularly. I always do the A303. If it slows down at least it's pretty.

M4/M5 - my satnav always tells me the 303 is going to be quicker, but every time without fail it’s wrong!

The M4 is closed this weekend between J6-8 I believe so that will influence your route options.

I would leave no later than 5am from London otherwise it'll be a nightmare whatever road you take.

I live just off the A303. Avoid it if you have an alternative and take the motorway, it's always jammed. However, there is also a route-around you can take which avoids Stonehenge (the worst bit) if you come off the road and go through Bulford then back on again after Stonehenge. Satnav won't show it as it technically adds10minutes to the journey but you can sit for an hour on that section of A303!

Can you go earlier? Its changeover day, which is probably obvious as you are going, but there will be thousands doing the same thing, out by 10.00.a.m, in by 16.00pm.

Leave at 02.00!!

Too late for M4 it closed at 8pm tonight between 6 and 8/9 till 6 am Monday morning.
You could M3 to Basingstoke cut up A339 to Newbury and on to M4 there which as everyone else from London will be going A303/M3 could be quicker if longer.

They'll both potentially be awful but you have a better chance the M4-M5 will flow. You'll start regretting A303 at Stonehenge, then again at Winterbourne Stoke, then Yeovilton, and by the time you are crawling into the Blackdown Hills you will hate your family and have nowhere decent to stop for a coffee. It's a MUCH prettier road but never attempt it westbound on a summer Saturday, or eastbound on Sunday.

I reckon M4. If you are still reading this, leave as early as you can, if you are west London, you'll be at Slough in no time to get around J6 to 8, it's only as far as maidenhead, then keep going.

Stop at the lovely diner at Sparkford for a milkshake, and there is a Starbucks on the road through the Blackdown Hills I think.

I sometimes overnight at The Lamb at Hindon, and you have to do the 303 to get there.

We drove down to Cornwall from NW London two Saturday's ago. I've always gone M4, M5 but took the traffic advice to go the M3 way. The M4 was closed for a junction for the day westbound which clinched it. Driving back last Saturday on the M4 and seeing the massive queue on the opposite side made me wonder if it's a weekly event. Either way, worth avoiding if possible.

I quite liked the M3 way, more varied and you see Stonehenge although I can see it might back up as parts are single carriageway. We left at 5.30am and the roads were very quiet.