To the best of my knowledge, the give away would be the colour of the road signs on the elevated part or on the slip roads leading up to the elevated section. If they are green ‘A’ roads then yes you can use it. If they are blue ‘motorway’ then Noooooo. I understand that the red tarmac indicates a bus lane. Does that bus lane give dispensation for bikes? Don’t forget, not all bus lanes allow bikes in them.
Your photo shows the Hammersmith flyover which doesn’t have any red tarmac or bus lanes. It’s part of the A4 so you are fine on there.
Your question though, included part of the M4 starting at Southall which does have red tarmac for the (in)famous M4 bus lane which bikes and taxis can also use. You can’t use the M4 at all because of your L plates.