Revisit direct debits and see if they are all still relevant - cancel magazine subscriptions and whatnot
Revisit all insurance policies and get new quotes - swap to cheaper policies. I've just saved £200 a year on pet insurance by doing this!
Meal plan and stick to it.
Download the olio app - loads of free food on there - well worth it.
Sell clothes, and other bits you no longer wear on vinted.
Sell books, old mobile phones on music magpie - cut out the scammers on marketplace.
Move savings if you have any to a higher interest account.
Check your bank balance daily - make this a habit.
Mobile phone - are you still in contract? Check. If not, swap to a rolling monthly contract or payg - keep your current phone for as long as possible, no need for the latest swanky upgrade ever.
Always use your clubcard/loyalty cards when shopping - those little rewards add up to perks.