Thank you very much everyone! That is really useful.
So I'm thinking that I got my wires crossed - NAV is therefore NOT an automatic flight mode - it is (as Hand Solo mentioned) an FD function (and therefore provides the "bars" on the PFD for the PF to fly?)
After take off, the FD would give you an initial climb at V2+10 Kt or above, speed that you'll maintain with the FD bar until the end of the noise-abatement
Thanks Lemurian - is there ever a situation where V2+10 (or the initial climb speed) would be greater than the speed for the selected flaps configuration, so that it would be necessary to clean up earlier in the climb?
Thanks again,
Martin