The system I would like would keep election in NI, Scotland and Wales separate from England. Reduce the number of constituencies by 30%. Each larger constituency to have an MP elected on a FPTP basis. But each ballot to show all national parties some with no actual candidate in particular areas. After the vote added up everything vote for each party in all constituencies in each of the 4 areas.
Then work out how many seats each party would have got under a total PR system, subtract the number attained by the FPTP vote to give a figure of the number make up members for each party. Where a party already has more than their PR share the other parties have their make up quotas raised pro-rata to make up numbers. Then each party has a number of make up candidates. Finally select the make up members from the top loosers in the main ballot.
Anger management!!! Help needed.