I think Avanti don't use P-coding. In any event, the NRCoT only even purport to apply the "timetable of the day" concept to Delay Repay - not to the entitlement to alternative transport under 28.2. There are also other provisions you could rely on (e.g. the PRO, which disallows any attempt by conditions of carriage to exclude or limit its rights).
I'd assumed that... until in September, both Northern Customer Services and Northern Control West did precisely that, flatly refused a bus replacement (for about 17 passengers), refused taxis to destination and even refused the cheaper option of taxis to the nearest station where an alternative train could have taken them to their destination...
Last train of the night, they were abandoned, however no surprise another more grown up operator
wiped Northern's bott rectified the situation, even though they didn't have to.
Despite being shown the final Sunday train departing at 11pm for six months Northern Control still tried to flatly deny there ever was a service at 11pm on a Sunday, then after more people were cc'd onto the email, changed their story to the recent 'timetable of the day' rubbish.