I currently go Bakerloo to Baker Street, then Jubilee to West
Hampstead, then NLL to Hampstead Heath.

This isn't great because NNL is only every 15 minutes or so, plus the
two changes.
Is there a better way? Bus?

BTW am I supposed to buy a zones 1-4 travelcard for this one, I
currently only buy a 1/2 but according to Wikipedia HH is in zone
3(eek!)