GDPR will be one of the first things to go.
Technically speaking, the GDPR has never had any legal effect in the UK because it's a foreign law and the 1689 english bill of rights says that no foreign prince, person, prelate, state or potentate has any jurisdiction, power, superiority, preeminence or authoritiy (ecclesiasticall or spiritual) within this Realme, so all EU legislation comes before parliment and gets signed off as a UK law to work around this.
In the case of the GDPR, it was implemented as the Data Protection Act 2018, so it's actually a UK law that in many areas goes further than the minimum requirements in the GDPR.
And in any case, I don't think there is any serious clamour to get it revoked. Business always wants certainty and stability, and doesn't want to deal with cost of implementing new rules so certainly lots of companies didn't want a bit of legislation that required everybody in the business receive training and that every company in the country had to put new stuff in place and argued against certain aspects of it. (for instance; allowing companies to ask people to contact a compliance department for a SAR rather than being able to ask anybody including the office junior who may not have understood the significance of the request)
But once all of that is done then it's done and we'd really rather not change it at all, because having implemented it then any changes are additional costs which nobody actually wants.