The MS nurse can’t prescribe drugs. If the consultant wants you (and you want) to start a disease modifying drug, that can only be prescribed by a neurologist.
It seems that you’ve been diagnosed and then left to get on with things on your own.
If in addition to being given the name of the MS nurse, you were also given contact information, then try contacting her yourself. Otherwise, As Carole said try phoning the hospital and either asking the hospital switchboard or asking for the neurologists secretary to get the contact details. In my area, the MS nurses work from a separate location to the hospital, so I doubt that I could get contact details from the hospital (which is why I’ve suggested the secretary).
In your situation, you could wait ages for the MS nurse to contact you, better to take the initiative. You can then discuss with her your drug situation and options. See if she can advise you.