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I prefer engineers twist drills. I find they work better than the brad point bits which seem to wander more. I bought a set of blacksmith's drill bits which go up to around an inch and as a set weren't that expensive.
12.5mm is not an odd size or expensive if you go to the right place.https://www.ukdrills.com/catalogsearch/result/?q=12.5mmI normally buy from their eBay store though. As a part time machinist I often need drill bits in .1mm steps and for decent quality drill bits are no more expensive than any other size.