If you live really rurally, fuel can be a massive issue, but you can reduce fuel costs, especially for a month.
I'm assuming you have multiple cars- can you manage with just one at least some days? Whichever one has better fuel economy, try to use that one and lift share e.g. to work etc. If you work in different directions, investigate whether being dropped at a train or bus stop would be cheaper than driving.
Try to only do maximum of 2 journeys each day, so if you have to e.g. go to the shops, do it on the way home from work, rather than a Saturday morning etc. Or it may be cheaper to get groceries delivered (also helps in terms of sticking to a budget).
Work out if it's cheaper to shop at just one place, or whether you're better off doing e.g. a bulk shop at a lidl then driving to tesco for top up.
If you need to drive to an expensive corner shop to e.g. pick up a pint of milk, don't! Just do without until you're next in town!
In terms of groceries- use what's in your cupboards/freezer up, and you can stock back up next month. And meal plan, and if you can limit yourself to one shopping trip per week, or one delivery per week, that will reduce your spending. Once it's run out for the week, it's gone!
Do you have any reward points etc for anywhere that you could use?