ye its ok to tile on plasterboard i usually prime with bal APD and would use bal whitestar depending on the size of the tiles, if your tiles are larger than 300x300 your looking at using a cement based adhesive.
hope this helps.
After checking with a branch you are ok to tile onto plaster beoard as long as its primed before. Using Bal Bond and then use either Bal white start or Ardex 330 for adhesives.
You're OK upto 32KG of tile & adhesive per m2 on plasterboard which should see you alright for upto about a 12mm tile in ceramic if I remeber corectly.
If its been skimmed this drops to around 20-22KG per m2.
No need to prime plasterboard if using tubbed stuff as it's not cement based.
Not sure, but maybe some makes of tubbed addy specify you prime first - but I've never come across any.
You don't need to prime , but priming does reduce the suck rate of the moisture from the adhesive thus giving that little bit more open time and allowing adjustment of the tiles if needed........