Could I plug this in my TV https://www.roku.com/en-gb/products/audio/roku-streambar it's old LG one with optical cable socket.
The relevant bit of info you need from the product intro is this...
Breaking this down into the bits relevant to you and your gear:
* sound from your TV will get to the sound bar via optical
* to see the Roku menus and any stuff being streamed by the bar you'll need to connect the supplied HDMI cable to a spare HDMI socket on the TV
That all appears to be fairly straightforward, but if you have any extra questions then just fire away.
"Will Streambar work on any TV?
Yes, Roku® Streambar™ will work on any TV with an HDMI® port. For a one-cable setup, you’ll need a TV with an HDMI® ARC port. If your TV doesn’t have an HDMI ARC port, you can connect with the HDMI and Optical input ports. Follow the quick on-screen setup to connect to your wireless network and link or activate your Roku account—you’ll be streaming in no time. Remember, to enjoy 4K and HDR entertainment, you’ll need a compatible TV and streaming channels."Breaking this down into the bits relevant to you and your gear:
* sound from your TV will get to the sound bar via optical
* to see the Roku menus and any stuff being streamed by the bar you'll need to connect the supplied HDMI cable to a spare HDMI socket on the TV
That all appears to be fairly straightforward, but if you have any extra questions then just fire away.