This document gives the industry's party line :http://www.rgsonline.co.uk/Railway_Grou ... ss%203.pdf
The web site also contains a number of other relevant guidance papers.
But as David said, speeds will determine what you should do.
You would only use theatre type indicators at low to medium speed since they are not readable at high speed.
If the through route is fast (typically needing a "stand behind the yellow line" warning on the platform) you would use feathers, officially called Position Light Junction Indicators (PLJI); normally no feather is used for the main route, but there are exceptions where it makes for greater clarity.
If the speed over crossovers into the lesser platforms is much lower than the main, the signal into those platforms might be approach released from red, that is, it only clears as the train gets near it, limiting the preceding signal to single yellow and forcing trains to slow expecting to stop at the junction signal. This could be necessary if you are using theatre type indicators, so that trains are made to slow sufficiently to be able to read the indicator.
Whether the junction signal clears to yellow or green will depend on the platform's departure signal, which must obviously be Yellow or Green if a Green is to be displayed on the 3-aspect junction signal. If permitted speed through the loop platforms is much the same as on the main, the signal into the loops would also clear to green provided the signal back onto the main is showing a proceed aspect. All three departure signals could also have approach controls if necessary for speed limiting purposes. If any of the platforms were a terminal bay rather than a loop, the signal leading into it can only clear to yellow at best (since the Moorgate accident).
Different rules applied at earlier dates, so if your model is historical, you would need to specify approximate date and company.