Other than removing the right to take appeals to the European Court of Human Rights, nothing will change. Admittedly there will he a need for a lot of legislation to amend or replace current laws and regulations that reference the ECHR, but given the low number of UK cases that are taken there anyway, ( on average about 10 a year ), it's really a pointless exercise.
https://commonslibrary.parliament.uk/research-briefings/cbp-8049/