Shipping in Woocommerce problem

apologies if this is in the wrong area of the forum.

\basically in short i have 3 shipping rates set up for certain products, so i have assigned these in the product settings.

Now the issue i have is certain postcodes need an extra ￡30 adding on to the standard shipping rate for the specific product,
so a: is this possible at all b: is there a free plugin which does this or a paid one which is guaranteed to do it

kindest regards
Mark