I find that when I write down every single penny I spend (with a pen and paper, not on the phone), so every little thing, every coffee, every bar of chocolate, and every large item, I really notice what I'm doing, and find it easier to cut back on the things that aren't essential.
There must be other places you're spending than just your list?
Car insurance sounds high, is it £70 per month? (£840 per year?).
Have you checked re gas & electric if you have credit in your account? Sometimes the direct debit is more than the bill, but they keep taking it (eg through the summer to pay for winter increase), but you might have quite a credit and could get some back if that is the case, alternatively, ask about switching tariffs?
Again, petrol sounds high per week, but am guessing this is for going to school or work, but are there little things you can do, for example, if your boot is really full can you empty it, to make the car a little lighter and use marginally less petrol), just being mindful?..
If you do your food shopping at the end of the day, there are often reduced items too so you could maybe cut back there.
There's also an app, and I can't remember what it is called, but it is where local food suppliers/stores sell off 'leftovers' at the end of the day for a fraction of the cost. A lot of students use this app and that might be helpful too.