Addirtional cost of H1 slab?

Hi all,
I will be doing an owner builder kit home (PAAL) hopefully soon and I am still doing some budgeting. I am at a crossroads at the moment with costs. Mainly to do with additions ( Alfresco area and verandah in front) and the additional slab costs.
The alfresco and verandah will add another 54m2 to the house and ergo slab. I have a rough price ( $100/m2) from 1 concreter for a "standard" raft slab.
So what my question is what percentage higher is a slab for H1 soils? This is only for a guide for budgeting. I understand this is a bit of "how long is a piece of string" type question but any help would be appreciated.

Second question: In QLD, can I lay 20m2 of pavers (uncovered) without a permit?

Regards
Andrew