Can you please give me some advice?

I have recently had an extension built on my home. Internally it incomplete, it still requires plastering.

Ive run all the electrics to the sockets light circuits etc, and the drops on the walls are encased in channel.

the extension has also allowed us to have a change around inside, allowing us to have a family bedroom and an en-suite to our bedroom,
by creating 2 new stud partitions (the builder put them up when he built the extension).

What i would like to know is where do i stand in completing the electrics for the extension and the 2 new bathrooms as far as regulations etc are concerned???

Any advice, greatfully received............