Divided England after the Norman conquest is unlikely, but the others can probably all be reasonably accomplished with a PoD in the HYW era, as long as it takes place before Wales is fully broken, sometime around the end of the aforementioned war. Stopping the Tudors might help Wales to feel more like it is being occupied by foreigners, and give them a situation where they solicit outside forces to help them secede like Ireland did in OTL. One successful intervention is all it'll take to free Wales, and a little while of competent rule to get it to stay that way.
Ireland and Scotland are fairly easy in this scenario, Scotland just has to remain allied to France and not form a union with England, while Ireland can break away either by native uprising, or by having an ambitious Englishman take control during a period of civil war and refuse to submit to the crown. As for splitting England, not of their own accord, but if they lose a major war with France, the French might install a puppet regime over a portion of England and alow another part to be free, similar to OTL's Vichy France