I come through the M4/M5 interchange at about 6pm on Fridays and it's usually pretty clear going from one to the other, the few times I've come straight from work to Caldi I've been there by 6:30, as soon as you're on the old bridge road (not sure of the number, A48?) you're laughing.
But you should all just buy micros and come to WORM every 2nd and 4th Tuesday