As I suggested, some teachers may do things a little differently. But I think ngondro is pretty important and though not everyone receives a lung from their main Guru, I think at the same time the reading transmission is often an important part to play in terms of not only receiving the blessings of the unbroken lineage, but also the blessings of the Lama who agrees to give the lung. Some teachers are happy that a student has the aspiration to undertake something like this and will often give it knowing that many students eventually give up the practice. But other Lama's give a little time to bring our sincerity to the forefront and often is the case where a student needs to request (even a few times) a lung or wang, etc.
More on topic though, is that there are many, many lama's who are able to give the lung for the Mahamudra ngondro. Sometimes I think a bit of travel to receive what is important to us does our practice some good. Not too many of us are lucky enough to say that our teacher lives in our very home town, so sometimes we have to do what we can. To the OP, on a practical level, try to generate merit and make strong aspirations to receive the lung, and I think it will all work out
BTW, I had to travel twice...once to ask the teacher if he would give it to me and then after following his instructions, again to formally request and receive the lung. All this to begin ngondro, but so worth it!