Many GPs believe intolerances (or delayed reaction allergies) are the same as fairies... the product of imagination. So be prepared to be rebuffed. We were for a couple of years until DS had a reaction to peanuts... but even then it took them another 18m to offer an appointment to DS. Most babies with dairy intolerance may outgrown it sooner than that.
If you decide to avoid dairy completely in the mean time, here are some of the things that you may need to avoid:
-all kinds of milks, cream, butter, margarine, ice cream, yoghurt, cheese
-Casein, casseinate, hydrolised casein, whey and anything with the prefix "lact" with exception of lactic acid.
-Many processed foods contain it including bread, ready meals, sausages, ham, frozen potatoes, etc. as well as some medicines (lactose)
To substitute you can use rice, oat, or soya milk but I would avoid almond milk. There are many soya based milk substitutes.
Foods with high calcium content include meat, legumes, oranges, apricots, sardines, salmon, watercres, figs, broccoli, spinach,and.... CHOCOLATE!!! (but check first that it doesn't have milk in it)