@upsydaisysims Are you willing to buy a used laptop on Ebay? To be honest, buying a new computer for €250 would be wasting your money. Anything in that price range is going to run Sims 3 and 4 very poorly, even on the lowest settings, and might well not run either game at all. And the laptop wouldn't be upgradable either. It's not a question of being a casual player and accepting less-than-ideal performance; the games might constantly freeze and crash and make playing effectively impossible.
And to be precise, Sims 3 is actually the more difficult game to run at the lower end of the spectrum. Sims 4 is as demanding, if not more so, on higher settings, but it will run okay on some lower-end laptops that couldn't handle Sims 3 with more than the first few expansions. But laptops in the €250 range aren't even going to handle Sims 4 well.
So if you're not interested in a used computer, I'd suggest saving up or otherwise waiting until you're comfortable spending more like €400-450. Prices will depend on sales and other factors, but I would fully expect to find a good-enough laptop for both games in that range.