What's invy like in NW ? I usually sail at Sanny back beach , but no good in NW , only a few days left of holidays .

Invy with anything N in it is very gusty. Short runs at low tide with mid tide you can launch from the carpark and run out to Point Smythe.
Swan Bay is great with any N in the wind direction. Long runs with water generally no higher than chest high. Downside - muddy bottom, weed fin and booties a must. Launch from Queenscliff Lonsdale YC - King St Queenscliff

what about portarlington and point henry on northwesterly ?

All a bit too far away , I'm at Phillip Island

Sail at COWES ,much better.flyns is great on a strong nw

I mite head out to Cowes this arvo , if wind picks up , too far to walk at Flyns .