@bellalala93 You can get an excellent laptop for Sims games, and in general, for £1,200 or less, or even under £1,000 depending on your preferences. In your price range, the best graphics card is an Nvidia 1660 ti. It's overkill for both Sims games, but running Sims 4 on ultra graphics settings may require more power than the next cards down (an Nvidia 1650 or an AMD 5500M) in a year or so, depending on how demanding future expansions turn out to be. The next card up, an Nvidia 2060, is only a bit faster, but it's usually significantly more expensive.
If you're willing to wait a month or so, this HP is a great option. It's available for pre-order on a few different sites; the lowest I saw was £950. In addition to a 1660 ti, it has 16 GB memory; a 512 GB solid state drive, which is more than enough for both Sims games and all the custom content you could download; and a processor that's more powerful than either game could ever possibly use.
https://www.overclockers.co.uk/hp-pavillion-15-ec1009na-nvidia-gtx-1660-ti-16gb-15.6-fhd-amd-ryzen-7-4800h-gaming-laptop-lt-04y-hp.html
If you'd rather buy right now, there are still plenty of good options. This Lenovo is also £950. While its processor is weaker than the one in the HP, it's still more than fine for Sims games. The laptop has only 8 GB RAM, which, while technically enough for either game, is less than ideal if you like to multitask. But you could add another 8 GB for probably £50, and I believe without breaking the warranty.
https://www.overclockers.co.uk/lenovo-legion-5i-nvidia-gtx-1660-ti-8gb-15.6-fhd-ips-144hz-intel-i5-10300h-gaming-laptop-lt-013-lv.html
https://www.box.co.uk/81Y6005SUK-Lenovo-Legion-5i-15_2938435.html
Interestingly, you could get the same laptop except with an Nvidia 2060 for £1,000. You'd never need the upgrade for Sims games, but if you're thinking of playing other very new games at some point, the 2060 may be the better choice.
https://www.box.co.uk/81Y600DLUK-Lenovo-Legion-5i-15_2953873.html
This Asus is £1,000 with the same specs as the HP you could pre-order, except for the (easily upgradable) 8 GB RAM.
https://www.currys.co.uk/gbuk/computing/laptops/laptops/asus-tuf-blue-a15-15-6-gaming-laptop-amd-ryzen-7-gtx-1660-ti-512-gb-ssd-10205355-pdt.html
Another option with a 2060 is this HP, at £1,100 for pre-order or £1,150 now. It has 16 GB memory and otherwise the same specs as the Lenovo.
https://www.overclockers.co.uk/hp-pavillion-15-dk1024na-nvidia-rtx-2060-16gb-15.6-144hz-fhd-intel-i5-10300h-gaming-laptop-lt-04z-hp.html
https://www.box.co.uk/1L6F0EAABU-HP-Pavilion-Gaming-15-dk1024na_2958257.html
There are a number of other gaming laptops in the £1,000 range, all fine but not as highly rated as the ones I listed. The one other noteworthy model is the Acer Nitro 5, which has the best battery life of the laptops in this class. Battery life is never going to be great with a gaming laptop, since the hardware draws a lot of power and people should always play with the laptop plugged in anyway, but if you want a model that does better than its competitors, the Nitro 5 is a good option, in either the 15" or 17" chassis. This one also has the best gaming processor of any I've listed here, if that matters to you.
https://www.box.co.uk/NH.Q7PEK.002-Acer-Nitro-5-AN515-55-764B_2934864.html
https://www.box.co.uk/NH.Q8JEK.001-Acer-Nitro-5-AN517-52-75Z3_2934867.html
If you're curious what £1,200 would get you, this is a high quality laptop, with excellent performance for its hardware. (You definitely don't need to spend that money on an upper-tier model; I'm just including it for comparison's sake.) Gigabyte laptops get the most out of their components in terms of game and application performance, and they have excellent cooling too. This particular one doesn't have a great battery life though, and you may not want a 17" screen.
https://www.overclockers.co.uk/gigabyte-aorus-7-nvidia-gtx-1660-ti-16gb-17.3-ips-144hz-i7-9750h-gaming-laptop-lt-0a6-gi.html
I know this is a lot of information, but given your budget, you can get a laptop that does really well in the categories that matter to you. If you have more questions about any of this, please feel free to ask.