3rd course of Lemtrada

I had my second dose of Lemtrada last June. My neurologist has explained that a 3rd dose of Lemtrada is available, only if the first 2 doses haven’t fully dampened the MS or there is new activity.

I think I’m experiencing a new relapse. The only silver lining is that it’s a relatively small relapse. I was just wondering what are the NICE guidelines for me to be eligible for a third course of Lemtrada. I can imagine my neurologist telling me that I can’t have a third course due to x,y or z reason. Hence I need to know how i go about demanding a 3rd course. Has anyone had a third course? Or has anyone even gone from Lemtrada to another treatment? What is the eligibility criteria for Ocrevus?