NotamPro, I believe, simply parses the lat/lon of all the notams which it has downloaded. It will download the entire notam file file for the entire, say London, region.
There isn't a enroute/aerodrome distinction as far as I understand...it simply works at the lower level of lat/lon geographic locations.
Disclaimer: I have only read the manual - so I could be talking utter rubbish. If anyone can show otherwise please do post.
I usually download the latest FIR notam for London FIR, zoom the map in to cover the region I'm flying, then click on the dots and read the notams. As you click on the dots it takes you to the relevant notam in the text pane.
Having read this thread though, which is highly informative, I will need to verify it is showing ALL the relevant notams.