So my spell check has no visual indicators that it's working. i.e I put a load of rubbish into it and there's no red lines. Online the common solution is to go on languages and uncheck the "do not check spelling ungrammar" function under the proofing language. However whenever I do this (the box is already auto checked in a new document), then look again, its re-checked itself. I'm utterly at a loss here.

This is a setting that applies to individual characters, not documents, not Word.
Mastering the Spelling Checker by Suzanne Barnhill, MVP

Open your normal template. How to Open the Normal Template

Type a sentence that includes misspellings.
Press Ctrl+A and select all. Then check the setting for proofing language.
Make sure the box is clear.
OK
Press Del to delete everything. Ctrl+S to save.
Close the normal template.

Create a new document.
Problem still there?

If so, please prepare a sample page exhibiting this problem and post it in .docx format. I will take a look at it and help you fix the problem.
How to attach a screenshot or file in this forum.