Nottingham to Eton Dorney

[Jesus]

Have to do this journey next Friday to be at Dorney for 10am latest.
Am I better to go M1 / M25 or M69 / M40?

I see there's still roadworks on the M1 but do they cause much problem?

Also, I'm taking the dog with me so need to stop off on the way - any service stations en route that have somewhere to exercise him?

Thanks.