An hour ago, Avanti released Advance fare inventory for Sunday 19 May -- matchday 38.
Showing what utter Tory bastards they are, they have made zero seats available on Advance fares in Standard Class or First Class arriving Lime Street before 15:00 or departing after 18:00.
The exception is Standard Premium, which owing to technical restrictions on how they can sell these in advance, have to be Advance fares.
Also, the 12:42 departure from Euston arriving 15:04 is available with Advance fares (and just 1 in First Class!) if you want to take a wild chance on it running to time.