Blood Tests reveal what? Which blood tests next?

[HealthPort]

I have an autoimmune skin disease called vitiligo, I also have a number of other symptoms some include:

acne outbreaks

depression

anxiety

mood problems

slight ridging of nails

premature grey hairs

vitiligo as said

restless less at times

slight balance problems at times

and more....

I’ve had a few private blood tests and they have revealed a normal thyroid, higher cortisol levels, vitamin d insufficient (not deficient) and MCV 100 slightly high. I've put it down to a vitamin b deficiency (MCV) and started supplementing earlier this year but my active b12 was ok reading, still there are many other vitamin b's like folic acid, I also drink heavily at the weekend which can make b deficient.

Other things I want to test for are zinc and copper levels as these can effect skin.

Should I re-test the MCV to see if the 3 month of vit b supplement has worked and lowered it?

What about the copper and zinc test?

Any other ideas? I know vitiligo can cause imbalances and imbalances can also cause vitiligo, so I would like to know where the cheapest place is to get cheap but tests that test for lots of stuff.