A Wifi USB-stick, a WiFi PC-card or a WiFi-antenna that goes into your Ethernet connector. If a driver is necessary, be sure there is one for your old PC.
There should be shops in England that sell such.
Preferably I would do this without having to get a cable extension using some kind of device, so I'm looking for a helping hand to find the right device that will do it. I live in England.
Maybe something like this? https://www.amazon.co.uk/AKORD-Portable-Wireless-Extender-Repeater/dp/B00VD6Q2IO/ref=sr_1_5?ie=UTF8&qid=1476105551&sr=8-5&keywords=wi-fi+extender+usb