I'm very pleased with the YG (black band I think) spiral point taps I got from Cutwell Tools. I also got a spiral point tap from RS Components made by Dormer and that is equally great.

I didn't know until I joined this forum, but spiral point taps are for thru-holes as they push the swarf out the end, and spiral flute taps are for blind holes as they lift the swarf. Both types are much better than the normal sort you find in DIY shops, they can be put in a cordless drill and eat aluminium like cheese cake.

YG-1 Machine Taps - Cutwel Products

Eitehr of the first two on that screen will do you nicely. The 'MU' ones are general purpose, black stripe.