For 20 years my daughter has enjoyed goat's milk, yoghurt and cheese, sheep's cheese and mare's milk, but her main source of calcium has been nuts and fish. Good luck with it.
I understand that a milk substitute based on rice is now available. I would suggest that you check out your nearest health food shop and ask them for advice. Also, if your diet is on medical grounds, you could ask your doctor for a referral to a dietician for specialist advice from a qualified professional.