@kerryphilp946 With your budget, there's really only one tier of laptop to consider. This tier includes a few processors and graphics chips that are all within a few percentage points of each other and can run Sims 4, all current packs included, on medium-high to high graphics settings. All of the laptops I'm listing are in this tier; the differences are storage and screen size, and of course price. For storage, 256 GB is enough for Sims 4 and about 100 GB of user content (saves, mods and cc, etc.), so while 512 GB is nice to have, it's not strictly necessary for Sims 4.
These are the cheapest options of this performance tier I found, at £300 and £330, respectively. They're the same model except that the second one has double the storage,. If you want the first one, you may need to buy right away—it looks like this offer is only for a limited quantity. But the second option doesn't appear to have that limit.
https://www.dell.com/en-uk/shop/laptops-2-in-1-pcs/inspiron-15-laptop/spd/inspiron-15-3525-laptop/cn32510sc_cc_lqd?dbp=1
https://www.dell.com/en-uk/shop/laptops-2-in-1-pcs/inspiron-15-laptop/spd/inspiron-15-3525-laptop/cn32511sc
This is the only other option I found with 512 GB storage, for £350:
https://www.argos.co.uk/product/2994066?clickPR=plp:24:55
In case you don't like any of those for one reason or another, here are the equivalent options I found, although they all have 256 GB storage. The first two are essentially the same laptop in different colors.
https://www.hp.com/gb-en/shop/product.aspx?id=4H2X5EA&opt=ABU&sel=NTB
https://www.currys.co.uk/products/hp-pavilion-14ec0537sa-14-laptop-amd-ryzen-5-256-gb-ssd-blue-10229545.html
https://www.currys.co.uk/products/hp-15sfq2570sa-15.6-laptop-intel-core-i5-256-gb-ssd-silver-10250738.html
If you have more questions, please feel free to ask.