Get one of these. Wiring is easy enough & you'll be able to control the speed.
https://www.amazon.co.uk/ARCELI-Voltage-Controller-1803BK-Adjustable/dp/B07RHMMM9W/ref=sr_1_5?_encoding=UTF8&c=ts&dchild=1&keywords=Motor+Speed+Controllers&qid=1607216191&s=industrial&sr=1-5&ts_id=10256315031