Alan wrote:
Because small (1/4") routers have smaller guides which don't fit the
templates.
I perhaps should have made this clearer.
From memory, they need a 30mm guide.

Hmm,

I made a partial arse of my cuts for my worktop, as I used a different
cutter diameter to the one specified with my jig, and used the collet
supplied with my router.

I was sure this would have been fine as I used the same cutter to cut
both the male and female parts of the joint, so, the radius of the cut
was ok, but the start of the joint was skewed somewhat (it happened
further down the female part of the joint.) but the cut itself was a
good fit, just needed a little relieving with a sharp wood cutting
junior hacksaw blade.

Not ideal, but saved me buying a 1/2" worktop cutter :-)

Cheers

Paul.