I managed to get this in a working state. For anyone that comes across this, the setup, it's not ideal, if you can change the LNB, do, but for my use case, it's fine for now.
The SQY Q LNB requires a different low frequency offset, which are read only in tvh. I've read that you can change this and build from source, but I went a different route.
I've installed MiniSatIP and used the command minisatip -f -L *:10410-0-0 to set the LNB settings. TvHeadend then picks this up as dual SAT>IP tuner.
I've created 2 separate networks in tvheadend. One for Horizontal and one for Vertical, assigned them to the correct tuners and manually added the required Mux's to each.
This is all working but due to the polarity split, the auto mux scans don't work well, so there's a fair bit of manual effort