writers block

I haven't posted anything so long that it's starting to get daunting, so will just have to write and get over it. While I am fairly sure that most people would regard this as a good technique for getting over writers block, I am generally not able to manage it. Blogs are less daunting than many other forms of writing I guess. For instance, November is 'NaNoWriMo' or 'National Novel Writing Month' (the 'national' is a misnomer, it's a global, internet thing originally I believe). Now there's a daunting project- writing a novel in a month. I would be keen to do this, but I am just overall daunted at the prospect. I'm just a chicken, basically. But I have been thinking about my latent novel idea (c'mon, everyone's got one, right?) and wondering what to do with it. I've thought about rejigging the narrative structure to make it easier to tackle, which seem right, but there are a few obstacles I keep running up against:

1. My idea for this novel was inspired by a story I heard in a Medieval history lecture in first year uni, about a pope (I think Gregory the Great) leading a procession through Rome against the plague. But when I came to look for this story later, I couldn't find it. Did I imagine it altogether? If I did, will I have to abandon the idea in the name of historical accuracy or should I just include it as a fictional event?
2. Which leads me to think- how should I approach the historical aspects of this story? It's set in the early Medieval period, it will require some research, but I personally am not a big fan of 'historical fiction' per se- or rather what I perceive as historical fiction, I enjoy some things that are set in the past. I think maybe this is because I would prefer the story to take precedence over the setting, and I feel happy about taking liberties with the accuracy of the setting and focusing on the story. But would that end up being even more annoying?
3. The idea requires a female heroine, but it's a bit of a juggling act in a Medieval setting- how do I approach the whole issue of women's roles in the past? I don't really want it to be the main issue, but it has to be dealt with one way or the other.

I suppose what I should do at this point is take my own advice and start writing something, but as I said- it's daunting! Anyway, don't expect a novel by the end of November from me.