Does the TV support pass-through on its HDMI/Optical ports? If that is available, I would enable that feature and ensure Dolby 5.1 audio-out is configured on the skyQ box (if necessary). The pass-through on the TV ports will stop any interruption/processing of the audio data received by the TV. 
 

If the feature is not available, then another option is to use an external audio-splitter with pass-through support. The SkyQ video and audio will pass-through that and split the video off to the TV and the audio to your Playbar in a far more timely manner. 
 

Examples of such audio splitters can be found within various threads on this forum with a quick search and at places like Amazon. Just ensure they support Dolby Digital 5.1 and have optical audio out support.

Thanks for the reply Ken. I just checked and pass through is only available via the HDMI e-ARC. 
 

I did however check the sky Q settings and I had the Digital audio output HDMI set to Dolby Digital Plus rather than just Dolby Digital. It states on the one below for optical output that if Dolby Digital Plus is selected for first HDMI setting then the optical output is disabled …. so that’s maybe where it’s went wrong. I’ve now set them both to just standard Dolby Digital. Hope that makes sense.

Yes, that makes sense. The playbar doesn’t support the DD+ codec and it maybe the case the TV was transcoding the codec to DD or PCM - I would set the TV ports to use pass-through as it applies to all the HDMI ports and I suspect it will work for the optical port too (it does on most newer TV’s) then see how it goes with all on Dolby Digital 5.1.

If problems persist try powering all your devices off fully (not standby) for 30 seconds or so ... and power them back on to renegotiate the  codec handshake between the SkyQ and the TV and hopefully all will then be well.

You always have the audio splitter option to fall back on if the lip-sync problem does persist.