But if you are on the A10 (Great Cambridge Road) then you'd be better
off joining the A1080 up to Wood Green then join the A105 to Manor
House and the A503 there.

That's Green Lanes through Harringay isn't it? Not too keen on that myself.

Me neither, which is why I suggested the parallel Wightman Road.

If you don't fancy the A105 between Wood Green and Manor House then
you could use A504 to Hornsey and the parallel Wightman Road to the
top then left into Endymion Road to rejoin the A105, or alternatively
take the A504 a bit further then left into A103 Tottenham Lane and
through Crouch End and Hornsey Road until you rejoin the A503.

Has Wightman Road got speed humps?

Wightman Road itself has no speed humps but all the roads connecting
it with Green Lanes do, together with 20mph speed limit and are one
way, except for Hornsey High Road (A504) and Endymion Road.

Cheers for all this - all this knowledge will come in very handy one day.

I have done these routes many times.