Hi Sam,
Welcome to Beoworld!
If your TV doesn't have a headphone socket fitted then you need to get a Beoplay S8 Connection Hub (£149 GBP from your local B&O store) to connect between the TV optical output and the speaker - this will convert the optical signal to audio and give you control of the speaker volume via the TV remote.
Please use an optical cable from the TV to the S8 Hub: link
Please use this cable from the S8 Hub to the Beolab 7-2 speaker:
Location: The cable workshop, England
My B&O Icons: