Yes, but you get what you pay for. If they can only afford something like a £300 car then obviously they should expect to buy a heap of shit. Quite frankly half of the buyers can’t afford tax or insurance anyway & should take public transport.
Running around fannying about with scrapyards, locksmiths etc. on a banger to get the locks working isn’t worthwhile. I guess it’s different opinions on the best use of your time but I’d just bomb it out as it is. It’s just a knackered old Clio & will always be just a knackered old Clio. You can’t polish a turd.