In skype conversations and the subtitles of a lot of shows I see たら being translated as "when" in some of them it seems quite morbid almost to use たら for example 帰ったら to me sounds more like "if you go home" Implying that there is some possibility that you might not get home. Is たら more certain than the English "if" or is this just a translation done from context?
How certain is たら?
This question reads like asking, "How certain is if in English?" Nobody can tell exactly unless they know the full context. Also, it depends on what you say. If you say something like,
If (when) tomorrow comes, let's go on a picnic.
Is there any chance that there will be no tomorrow? Yes, if a nuclear war breaks out today, there will be no tomorrow for us, but how likely is it?
帰ったら can imply both. But if the following clause indicates an immediate action, it could have more certainty.
When (If) I come back from outside (other places), I always brush my teeth.
The following link Japanese Conditional Form - Part 4. ~たら (~tara) Sentence will help you better understand it.
It does mean "if", but it feels quite likely you will do it. So it often can be interpreted as "when".
The level of certainty and whether to use "if" or "when" can be understood from context.
帰ったら、電話してね！Call me when you get home ok!?
Here we have a follow up action, so it is pretty much implied you will be back. There is a chance you won't go back, but that would be something like getting lost or killed on the way.
帰ったら気をつけてね！If you go back, be careful!
Here, the follow up is related to the event of going back, and not what to do after you go back, so much more "conditional".