I agree with others - the drive is actually interesting for seeing the real country-side. 3hrs IIRC and Zambia is a safe country and the road is fine. No need to fly.

I'll echo others' recommendation for white-water rafting. It's great fun and definitely the best river I've rafted in. It has the advantage vs European or N.American rivers of having warm waters so when you fall in it's actually very pleasant.

It was in October and didn't feel like it was dry at all.

Go!