Cheers for the pointers - much appreciated! Think you're probably right - need to hit them hard and fast.
In my xp, backed up with a vamp, you're looking at 40 attacks for, say 20, in a big block. Then you've got danse from a necro, letting them attack twice. Granted, you get to swing back before they attack the 2nd time but with a big block you'd still likely be looking at 20 zombies attacking again. That means, all in, you're looking at 80 attacks. This averages to 13/14 mortal wounds in addition to any attacks that get through and which you, inevitably, fail to save.
With their nuts pile in rules they're super quick and don't need to charge. Plus they come back really easily when fighting infantry. I've had a Stardrake be popped by zombies getting the jump on me. They're horrible little s.o.b's.