We are going to a wedding after Christmas in Angles sur l’anglin and we are wondering if anything will be open in the lead up to Xmas and what we could see
I don't know what you might be expecting to be open or closed but there are people who live there who need essential services so those things will be available. If you were wondering about sites and attractions there is no general rule so you'd need to check the website for any site/attraction that might interest you. As far as what to see and do you can check guidebooks for that region as well as the tourist office websites for that area:
Poitiers as a city is much more residential than tourist, so the main differences between summer and winter relate to weather and daylight hours rather than the number of people around. There is quite a significant English ex-pat population in the general area (my sister being one of them) so may well find it a little more anglophone-friendly than many French rural cities.
I was in Poitiers last summer. There's really nothing much to see and do there if you aren't interested in going to Futuroscope. I wouldn't spend many days there for sure. They do have a very nice small regional museum, though, with both art and some archeological artifacts.
the main church is worth a visit for the internal decoration, irrespective of your religion. On the lead up to christmas they usually have a nativity scene with real animals and previously they have had a light show with images projected onto the facade of the church. We sometimes visit the city for lunch if we're passing through but agree we've never found much in the way of 'tourist' activities