It’s solved now! 😊🙏 Thanks to all who helped and especially Guy.
You can see my TVs info in the attached photo below. So the remote that came with the TV is the MK1 version (the middle button on the second row is AV).
The manual for Beo4 can be found here: http://www.iconic-av.co.uk/manuals/beo4_mark1_av.pdf
I used the ADD function on page 10 to add TURN.
STORE was not available there so I added V. SETUP (which holds STORE within that menu).
TURN is only shown in list under V. TAPE and since the Decoder on/off is under TV I had to cover the end of the remote when I pressed V. TAPE to use TURN (via the LIST-button). After this I went into V. SETUP to use STORE.
Hope this clears it up for anyone else wanting to use VTAPE 2 with a single press on the TV button an MK1 Beo4 remote.
This is my MX7000:
