Is it possible to use my laptop as a screen and keyboard on our pc?
Trying to declutter our small room and a rarely used complete pc takes up a fair bit of room.
Before anyone asks the data on the pc won’t fit on the laptop.

Remove screen and keyboard from PC after sharing all the files you want. Connect both to network and use the laptop with shares to the PC

I am an idiot when it comes to this. Is it just a case a plugging one into the other?

You can connect them over a network (WiFi or LAN) and use remote desktop or something like VNC to access the PC from the Laptop.

You can connect them over a network (WiFi or LAN) and use remote desktop or something like VNC to access the PC from the Laptop.

Probably worst of both unless PC is much higher spec and still not the best.

Use the desktop as file storage, put things into proper organised folders under one main folder and share that. When you open the laptop all files are accessible by looking under the network bit in windows explorer.

If the laptop is not up to the job consider replacing both in one.