K is the lowest needed not L, though not all Ks are suitable.
Its likely yours will already have a K
Youll need to scan your CAN Gateway with VCDS and post up the SW and HW revisions of it.
Mine had a K and it was absolutely fine.
Mine is the following - same as SteveP
Address 19: CAN Gateway Labels: 1K0-907-530.lbl
Part No SW: 1K0 907 530 K HW: 1K0 907 951
Component: J533__Gateway H04 0020
Revision: H04 02 Serial number: 281106F1001231
Coding: 3F0F034007000001
Shop #: WSC 01287 785 00200
VCID: 2F671974C78D