About to ask for JD update + pay review - advice?

As the title says, after 5 years in this place I am finally about to ask for my Job Description (which really doesn't fit my job well anymore) to be reviewed, also as part of that to be upgraded to full-time instead of term-time+5-days plus a salary review based on my increased roles & responsibilities too.

Any advice?
Is it a good idea to do this all at once?
I figured it'd be better to throw it at all the wall and see what sticks rather than keep asking for something else to be looked one after another. Yes, no?
Should I contact my Union beforehand, or only if things don't go the way I want (ie unfairly)?

I've already drawn up a document highlighting where my JD doesn't fit anymore with reasons as to why, along with my own justifications for wanting to be made full-time.

Anything else I need?
Thanks in advance for any advice :)