Wiring Extension advice

Now Im building an extension and this requires me to extend lighting and socket ring mains into new extension.
Now I have done basic wiring courses so would like to carry out the wiring myself then get an electrician in after and get it test(and sort any bits I need for the new regs).
Does this sound acceptable?
Also I was going to leave my bathroom to be done at a later date due to money and have not put a light in as I'm not sure what I'll decide on. Now is this an issue when I get it tested?
I was also wondering what the latest is on bonding in bathrooms/ensuite?

Best of luck finding a spark that will sign your work off.

As for info re: bonding read the regs