Driving Perth to Kent A1 or M6 on a Saturday??

Embarking on another road trip to see some family at the end of June. Driven down a few times but always the same way and always during the week. Go A9, M9, M80, M73, M74, M6, M1, M25, M20. Usually get quite lucky and miss heavy traffic completely until Birmingham and M25.

Going to go down this time early Saturday morning probably leaving around 5:30/6am and aim to arrive around 2:30pm/3pm and feel like going a different way for a change of scenery. Contemplated going M90 down to Edinburgh, city bypass until A1 and then A1/A1M, A14, M11, M25 and M20. How is the A1 on weekends, I know the road until Newcastle will be relatively clear that early on a Saturday but what about the rest of the way. Never driven on the A1. Will it be quicker, any points of delays or decent places to stop for food/coffee any help would be massively appreciated. 😊