I agree with Vick that I would not be so stress about what m/w and h/v say. While the NHS promotes Bfing and there are certainly some midwives and HVs who are over the top and perhaps even a bit disrespectful about a mother's choice, I don't think that it is the rule but rather an odd exception. I would not get panicky about it and automatically assume that is how they will be, without at least first discussing it with them.
Also, while large vomits are absolutely a sign of a milk intolerance, they are not the ONLY thing that it could be, and getting that medical advice is probably the best way to start out.
And as Vicku says NUtramigen is horrible stuff but at your LOs young age there should not be too much of a problem getting him to take it, should your doctor want to see if it is a milk problem.
They will not do allergy testing for a milk allergy, especially not at this age. The best way to diagnose a milk allergy in a baby is clinical diagnosis....examine symptoms, remove dairy and see if the symptoms disappear.
HTH!