Actually, the Synod of Whitby is too late for the POD, Toynbee not withstanding. It's the timeline I am working on. 2 small credible PODs in the 6th century which butterfly away a lot. I accidentally wiped out Islam, for example.
BTW, the Irish/Celtic Catholic missionaries were all over Europe by the Synod, even established in Italy.
In the British Isles, a map of the Irish monasteries may be seen here:
http://www.wesleyjohnston.com/users/ireland/past/pre_norman_history/christianity.html
The information on both maps are fairly widespread.
I have been lurking for years. I think I understand how to behave, except I am not certain exactly what a wank TL is, though I am afraid mine is. I have geological, meterological data to factor in, though I am mainly interested in cultural/technological changes.
At least, here, I am among folks who understand how absorbing and fun it is to work out an alternate timeline. With friends and colleagues (IT), if one tries to explain, they back away slowly.