The main people the British government do have influence with today are mainstream Protestants like the DUP and UUP. That influence has been used for good throughout the peace process. Any other suggestion is a lie. The peace process would have died again and again without the British government, particularly of Tony Blair.
You treat the Protestants in Northern Ireland as a side issue, oh they can stay if they want to...but remember to them they are British and already living in the UK. That is the problem.
Basically you are way out there on the extremes, being not in favour of THE peace process, but A (fictional) peace process. The great mass of the people of Ireland dont agree with you.
A little comparison 4U. Lets say that in the Philippines, an American majority province had been carved out when the US (nearly half a century after they first demanded it) granted their independence in 1946.... with its residents (including the Filipino minority in the province) deemed full American citizens.
Then "lets say 47 years later" (like the span between the 1922 treaty the Brits made Michael Collins give in to, and the renewal of Troubles in 1969 Ireland) the locals reacted to discrimination, and said "Yankee Go Home". And the US sponsored a Peace Process that "kinda satisfied" most (but far from all) on each side.
I'd side with the Filipinos, and say that such a 1946 "partition" had been accepted under duress; thus was no more binding than a ransom deal signed with a kidnapper. And that if the Filipino rebels welcomed the American descendants staying as full citizens of the Philippines if they wished, I'd say my compatriots should accept it.
The Native American situation is different, as if some ppl in England had a pure Saxon bloodline, and others were only descended from the Norman conquerors, with the Saxons having been badly mistreated like our "red man" has been.
In that case, compensation would be the only solution, as telling the Normans "go back to France" would be ovakill after 900+ years. (And the Americans of the past 600+ come from far more countries anyhow).
p.s. - I'd give Japan back all of Okinawa immediately, B4U mention that.