Hi, welcome to the forum
Jeyes KleenOff Household Ammonia is perfect - it is what I use
When i got mine it didn't say on the bottle so I emailed the company to ask the strength and they said it is 9.5%. Your tank needs just over 3 ml ammonia. I would add just 3, wait half an hour for it to mix in thoroughly then test to see what the ammonia level is. If it's less than 3 ppm, you can add some more - but make a note of how much you add altogether.
The best method for fishless cycling is the one I wrote in the Filtration and Cycling section
It was developed by someone else who did a lot of research in scientific papers, and this method is designed so that nitrite can never get high enough to stall the cycle. Other methods tell you to add ammonia too often which makes so much nitrite the cycle stalls.
Your hard water means that the cycle should be straight forward. High KH (carbonate hardness) usually goes with high GH (general hardness), and high KH does 2 things - provides carbonate for the bacteria to use, and prevents pH drops.
However.....
There are no cold water fish suitable for 110 litres except perhaps one single fancy goldfish. And there are not many temperate fish - zebra danios really need a longer tank as they are
very fast swimming fish; white cloud mountain minnows really need softer water.
But you have a heater, and tropical fish would give you a much larger choice. There is no difference in the care of cold, temperate and tropical fish. The only difference is the setting on the heater.
Tropical temperatures would allow you to keep the smaller livebearers (endlers, guppies, platies - the tank isn't big enough for swordtails and mollies) There are opther species as well, but living in a soft water area I don't keep them.
@Littlefish does live in a hard water area and has lots of fish, so she should be able to suggest suitable fish for your water.