Driving to Cornwall tomorrow, any tips?

[flowery]

We are travelling from Cambridgeshire. I realise the traffic will be an utter nightmare so looking for tips on routes to take, what time to leave (have been advised 3am, 4am, 7am and overnight so far), good places to stop etc
We have two DC 6 and 3 if that helps.

Am hoping the journey doesn't make me regret booking it!

Thanks in advance :)

I typed this yesterday but it seems to have disappeared - apologies if it's duplicated.

There are 2 farm shops within 5 mins of junction 39 m5 - Kenniford is signposted off the sidmouth road before westpoint, it's a small farm with a few animals to look at, cafe and play equipt/ride ons.

Greendale is further on on the sidmouth road (but not far) and is bigger with an instore butchers/bakery and cafe, animals you can feed and tractors to climb on.

Both infinitely better for a rest break than exeter services!!

Just wanted to say thanks again for this thread, we had two completely smooth sailing journeys there and back :) Went M4/M5 on the way there, left at 5.30am and stopped for breakfast at the big Sainsbury's - brilliant tip that was, clean quiet cafe, nice big store, got the kids fed and dressed and then picked up all the bits we needed. Got to the campsite at midday!

Did the A303 way yesterday coming home, left at 11.15am and got home (inside M25) at 5.30pm I have never had such an easy journey on a Sunday before, not one snarl-up anywhere. And that included a 1.5hr lunch stop at a brilliant pub in Ilchester, the Ilchester Arms - highly recommend it for anyone travelling that way, the food was lovely and reasonably priced, friendly service, nice garden with play stuff for the kids, even wipes and nappy sacks in the (very clean) toilets. And free parking nearby. Really good.

Holiday was nice too