I wish you luck. Do both, shoot during and after. You might be surprised which one will be best. The available light may not be too bad. From my experience I think they will most likely have the overhead lights on. Very few churches have good lighting.If you do get a chance to get in early and you have a good incident light meter, meter everywhere the wedding party will be with the lights off and on. The backlight would concern me a little, but I think you can work around it. I would always ask the pastor if it would be ok to use flash just for the kiss at the end of the ceremony. Most times they would say ok. I hope you will post some of the results after the wedding. I'd like to see how you made out.

I thought I remembered that, when Win10 was first announced, the update process was described as effectively mandatory. You would get what MS wanted you to have when they wanted you to have it. The stated purpose being that MS would insure all Win10 installations worldwide would be as up to date as they could make 'em, all the time. (And I remember the story of a local TV station that had their weather reporting display lock up in the middle of a broadcast, showing a Win10 update screen.)

Have they since modified the process so that users can choose NOT to get a particular piece of an update (as used to be the case), or at least choose to postpone updates to a date/time of the user's choosing? I bought my first Mac in 2012 and have moved most of our family computers to Apple since then, although we still have a couple of Win7 boxes - my wife has a laptop with a Windows-only music app that she uses constantly, and I still use my old desktop to just run some duplicate backup hard drives for my photo and media files. (Neither connect to the internet any more, and neither is being updated.) Our Apple computers do what we need and there is no reason to replace 'em at this point, but I do tell myself that if/when they DO need replacing, if I can't afford new Apple gear I'll teach myself Linux and deal with whatever software limitations come with it before I'd go back to Windows - in part because of what I thought I understood about their mandatory update policy.