When travelling back from Macclesfield to Coventry on Friday afternoons, many moons ago, I'd avoid the M6 / Birmingham altogether, taking the Cat and Fiddle to Buxton (well around the back via Grin Low Road) then take the A515 via Ashbourne, picking up the A38 at Alrewas, then the A5 and in my case the M69 south and round the A46 Coventry Eastern Bypass. You could follow that, and pick up the A423 to Southam and Banbury, thence to Kidlington via M40 and A34. Best described as scenic, and a good afternoon route when (pre toll) there could be significant queues heading south into Brum.