Sounds like you might benefit more from something like this: https://www.cutwel.co.uk/lathe-tools...holders-teknik

It will let you drill, bore, and turn all with the same tool and only take up one space on your tool post! It won't hurt the wallet too much either. The only issue you may have is that you're limited to the size you can drill, so anything smaller may be an issue. but it would work fine for your 12mm hole you need to do now, depending on the depth you need to bore of course.

You could also go down the route of ER holders like this: https://www.cutwel.co.uk/12mm-straig...o-c12-er16-80m

That way you could use any drill size you needed between 0.5 - 10mm depending on what set of collets you bought to go with the holder. This would be more expensive but a bit more versatile.