Pretty basic question.

I need to make 2 holes each about 30mm diameter in a cavity wall. Usual
brick external and block internal with blown fibre insulation.

What is the best way to go about this?

This is a one off that I don't expect to do regularly so I don't want to
spend a fortune.

I have a Makita drill with a 13mm chuck rated to 20mm of concrete.
Bricks are red 1960s and not overly hard.

Thanks for any advice.

(This is one thing I can't see a way to do with my angle grinder unless
I want to do a great deal of filling)