Hi
You would be better off buying an access point, you can get all sorts of issues with a router making it into an AP only.
If you can, for a one off effort, the best thing is to run some Ethernet into your loft (assuming you have a house with loft accessible) and install a proper ceiling access point, and this can be powered using power over Ethernet, so you don't need to run power anywhere. This will typically cover the average house easily given the high vantage point.
Even if that is not possible, you can still use the same sort of access point, either wall mount or site somewhere, these are typically miles better than Wi-Fi built into consumer router grade kit.
I've been using a ceiling mounted NWA1123-ACv2 from Zyxel. It's built like a tank, blends in like a smoke detector, and covers the whole house and beyond with ease. Expensive, but worth it, especially given how reliant on Wi-Fi we are these days.
Regards
Phil