Wessex falls to Danes

The Papacy will want to drive the Vikings from England because of the loss of prestige, a Christian land falling to pagans, plus the wealth of England and the increased threat the Vikings will pose if they hold England as well. [No/less forces tied up fighting English resistance and bases and wealth from southern England making attacks on France and the low countries easier]. They may well try something like a crusade although one problem is that the Vikings are even more dominate in this scenario. You have them attacking much of western Europe and besieging Paris twice in the 840's and new attempts might be made including Vikings settled in England. Hence, especially since assorted 'Saracens' are rampaging around much of the Med, while from the east the Magyars are starting to be a threat to areas in central Europe. Plus the Vikings are really the dominant naval power in northern waters so invading an island where the opponent has naval dominance is unlikely to go well, unless you get very lucky.

Also at the time the Catholic church was I believe less centralised at this point. A deeper crisis like this might prompt earlier reform of course and a more centralised church earlier.

I suspect its more likely that the Vikings will be Christianised at some stage. Too much advantage for powerful leaders in joining the church as it helps them centralise power plus some will realise that they can get more wealth from farming and trade than continued raiding. That would probably see a later re-emergence of England, as occurred OTL a couple of centuries after the Norman conquest, but with a larger Scandinavia influence - both because you can expect more Viking settlers and local English using their language and because you won't get things like the Harrying of the North which killed a lot of people, mainly in the northern Viking settled areas. Instead of the OTL Norman-French influence, which had more military political control but was a small but often brutal elite. As such you could see more Anglo-Scandinavian culture and England, and hence possibly most of the British Isles, orientated toward Scandinavia rather than France.

One big butterfly here, without a Norman invasion, which would seem less likely and less likely to succeed, would be that England wouldn't be drawn into wars in France anything like as much. This could mean England is more powerful in Britain and France might unify earlier - or possibly later without a perceived foreign threat.

Another possible one, with the Vikings more powerful and possibly more people seeking to escape the rise of kings and central power is possibly more moving to Iceland and possibly further west and an earlier/more general knowledge of the Americas, which could result in huge butterflies. Even if the worsening weather of the Little Ice Age ends any such colonies they will impact on the native Americans and also the western Europeans will know there's something out there.