For anyone who might wish to contribute to this thread, here are the system requirements for Sims 4:
https://www.ea.com/en-gb/games/the-sims/the-sims-4/pc/system-requirements
It's the graphics card requirement there which might well rule out many cheaper laptops but trying to make sense of the relative performance figures for different graphics cards is an absolute nightmare. I suggest emailing that link to these people (whom I've got total faith in, having bought loads of stuff from there myself) and asking them what they've got that meets your requirements:
https://accomputerwarehouse.com/
(Use the contact form here:
https://accomputerwarehouse.com/contact/ )
However if you've got £400 available, then go straight for this:
https://accomputerwarehouse.com/product/hp-zbook-cad-design-laptop/
That's an incredible bargain. (You'd have had to pay the better part of three grand for one when they first came onto the market in 2014). It would have no problem running SIMS 4.
If buying any refurbished laptop though (from any source) remember that the batteries in them are classed as 'consumables' by retailers, so they might not hold a charge for very long. Obviously that doesn't matter if the laptop will always be powered through a mains charger but otherwise you should budget for another thirty or forty quid to buy a new battery online.