As expected the draft legislation for the UK implementation of the pillar two global minimum tax covers only the income inclusion rule (IIR) at this stage. The undertaxed payments (or profits) rule (UTPR) draft legislation will be released in due course.
There is also for now no draft legislation for a UK domestic minimum top-up tax (such that UK profits would be topped-up to an effective tax rate of 15% payable to HMRC...