Same as a lot of other places, they sell the boots but not the liners.
Basically, a pac boot is only any good for sustained use if you have spare liners so one pair can be dried while another is in use.
The UK distributors of Baffin do not carry the liners in the UK because most UK users are not using them for sustained wilderness use and many of the US suppliers will not supply the UK because of trade restrictions or exclusive distribution deals.
I am currently trying to find a US postal forwarding agent to get around this PITA but otherwise I'm going to source some felt and make my own.