Has anyone extended their patio? What did you do?

We bought our house with a pergola, that we want to convert to a patio, but make it a little bigger. It has a slab underneath that will need to be extended slightly.

Has anyone bought a DIY kit? Dad is a tradesman, and DH is handy with tools etc, and I wonder how much money we could save doing this?

Does anyone know how much it would cost to get someone like Stratco to do the whole thing?

Thanks