like can i draw a line through the middle vertically and do like a diagram on one side and my working on the other side, or does that run the risk of the markers not seeing it(since ive been told they just zoom into the answers or something)?
you really shouldn't be ruling lines and doing half of your working on one side and half on the other side. you have no need to save space on writing booklets bc you can have as many as you need. its not something that might lose you marks on its own per se but its just not good practice bc it means you are probably writing too small or squishing working that could be more expanded in terms of detail. if you have a marker who can't see very well or if you are getting marks on details like the accuracy of the shape and scale of your graph or detailed expansion etc. you can see how the size of your work is a problem
its usually encouraged that you draw diagrams and graphs large enough to take up both sides of the page, about 1/3 of the page for questions that ask you to graph and if the question doesn't require a graph/diagram you can get away with it being smaller. my school teachers write "too small" in all caps on our papers when they are too small.
i personally think there is some leeway when the working for a question is very short and its like a 2 marker and it probably doesnt need that much detail or whatever. and i feel it is more beneficial to rule lines when the question is asking you to compare different scenarios and you are splitting the page (e.g. compare the interest collected on investment scenario a with investment scenario b). i find that side by side comparison in this sense is really effective in conveying your point as opposed to doing it one after the other ONLY if the question isnt worth a lot of marks