Thanks, NorthOrSouth and thijsseh. We agree on the 'no travel agent if possible' aspect!
I had not heard of Expert Africa and will look them up. They seem to offer the right mix, and I would think about combining your tips.
I thought that we may be a little premature in booking now for early next year. Except that I learnt in a friendly PM that polar bear opportunities for Autumn this year are already difficult, so we'll be planning now.
Thanks again.