Humbrol 29 and 30 are ok for the topside camo but as mentioned by others the undersides are 'sky' - Humbrol H90 is the one you want.
At 1:24 it may be worth considering using H163 in place of H30 which is going to be a little on the light side for the upper green.
although theres no actual plans for the scheme the colours used with each model can be found on ..........
www.airfix.co.uk
theres only one 1:24 Hurricane in the models list and its still a Mk1. The H28 grey you have is mentioned in the list but for what, i'm not sure.
i've got an origonal colour guide for the model so if you need any other help i'll dig it out for you.
hope this helps, a kit like that is worth getting right.
migs.