Absolutely re relay. no switch would last long without one, my comment was more to do with the need to have them only come on under two conditions,
a/ Main beams ONLY on
b/ special spotlight switch on.
Here is a tutorial including wiring diagram, which shows how to wire in the relay.
https://www.4x4community.co.za/forum/showthread.php/8006-Wiring-of-spotlights
There are tons of articles on tinternet but a lot don't mention doing it fully legally for the UK, i.e. to only come on in tandem with the High beam, so they can be confusing.
Best of luck