As has been mentioned, I can't really imagine long-term Wales being able to keep England at bay. Perhaps with a significantly more tame England, yes, but considering the conditions of the founding of modern England, that strikes me as unlikely. I can't even begin to imagine what change would be necessary to make them not a naturally aggressive country at this time.
Scotland and Ireland is a potentially different story. Ireland is physically separate, but is also catholic which is a definite strike against it. Not to say it isn't possible for them to remain independent, but not horribly likely, since there would be a rather strong conflict based on religion. That said, if they managed to make it not worth the trouble to conquer them, it could be possible if they somehow became unified. Even in OTL, though, it's hard to say that the Irish were a huge contributor to England in pre-empire days, so not sure how this would even change things.
Scotland, on the other hand, was relatively united and had a fairly strong strategic position. I can see them holding out against English rule for a time, but it would have to be a more political effort than military one. The Scots military doctrine doesn't seem like it would hold up to longbows too well, similarly to the French, so I don't foresee them expelling an actual invasion too easily.
That's on their own, though. I would say Scotland definitely had the strategic position to be an appealing target for foreign aid (unlike Wales) and the unification to not just fail anyways (unlike Ireland).
Overall, I just don't see any small manipulations that would cause this, outside of curtailing Norman invasion of Britain to begin with, and even that isn't certain.
Although I might just be completely wrong, as well, don't get me wrong.