Very possible. I am just taking in the scale of the changes suggested here. As a brief overview, the development of the English language, the default lingua franca changes dramatically and doesn’t become the main second language spoken globally. The exact circumstances that allowed the industrial revolution to take place in the UK is unlikely given that there’s not going to be the same UK, so I'll guess and suggests that industrialisation starts in Northern and Western Germany part funded through Dutch and possibly Swedish banks instead. And naturally the British-descended nations the United States, Canada, Australia, New Zealand and to a much lesser extent, South Africa don’t develop the same way, to say nothing of the other ex-colonies or current Overseas Territories whose histories are basically completely different. The Channel Islands remain French, Gibraltar stays Spanish, Malta becomes part of Italy eventually having been part of the Kingdom of Sardinia before - and that's just for starters.
As a guess we would have up to 11 states covering the whole of the Anglo-Celtic Islands in their place with 7 of them covering Great Britain itself:
1) Dumnonia – Cornwall, Devon, Somerset up to the Somerset Levels and western Dorset probably up to the River Stour with a capital at Exeter.
2) Anglia – southern and south-eastern England with a capital around London. The Anglian church is attached to Roman rites.
3) Mercia – a buffer zone in the Midlands up to the southern shore of the Humber Estuary and the eastern shore of the Rivers Severn and Trent with the River Mersey as a northern border. The capital is probably somewhere like Lichfield. Mercia is probably highly Anglian culturally and the Mercian church is likely attached to Roman rites.
4) Cymru – a greater Welsh heartland probably formed from a variety of sub-kingdoms which reach out as far as the Rivers Severn and Trent in the English West Midlands. Wales potentially unifies as a single Kingdom around 1057 under Gruffydd ap Llywelyn with a capital somewhere like Rhyl. The Cymru Church is a Celtic rite church.
5) Northumbria – a culturally mixed state combining Viking, Anglian and Britonnic traits north of the Rivers Humber in the south-east and Mersey in the south-west stretching up to Edinburgh in the north and along the line of the River Nith through Dumfriesshire, East Ayrshire and South Lanarkshire to the north-west. The capital may well be moved to Newcastle from Bamburgh eventually. The Northumbrian Church is a Celtic rite Church.
6) Strathclyde – a Gaelic-Nordic kingdom along the west and south-west of Scotland including the parts of the Hebrides and Mann. The capital is Dumbarton. The Strathclyde Church is a Celtic rite Church.
7) Alba – a Pictish-Gaelic-Nordic kingdom covering the north and north-east of Scotland and has its capital around Inverness. Alba is the most obviously Nordic kingdom but becomes Christian a little later and is part of the Celtic Church.
My guess is that Ireland will follow a roughly parallel experience as irl until the 12th century. Given a lack of unity in England, it seems unlikely there will be serious English presence in Ireland, which will obviously have a significant impact there. I am guessing some form of consolidation will take place meaning that something vaguely similar to the four provinces take shape using rivers and mountain ranges as natural borders. I am going to guess that some form of the following kingdoms are formed:
8) Ulaid (Ulster, capital Downpatrick; including the lands of the Northern Uí Néill)
9) Connacht (capital Roscommon; including lands of western Bréifne)
10) Munster (capital, Limerick; probably including substantial parts of southern Leinster and Osraige)
11) Mide (capital Dublin; includes parts of northern Leinster, most of Airgíalia and eastern Bréifne)
Under these conditions, the Synod of Whitby may well take place under different circumstances or arrive at a different decision in 664. It’s possible that in a post-Roman, Medieval Britain which is very different to our own for whatever reason, Celtic Christianity has a chance to develop in its own way, evolving into something like the Greek Catholic Church in Eastern Europe who is attached to but not part of the Roman Church. This could have significant consequences for foreign relations and whether Latin would become the language of law rather than a formalised version of Gaelic is another matter.
The Anglo-Celtic Islands may end up becoming a rather niche place with unfavourable weather speaking obscure languages, visited by relatively few and too busy fighting amongst themselves, unable to unite under an sort of shared purpose rather than looking outward for good and for ill as we did irl.