The problem here is that you have ADDED an example to what was on the BBC site. Your example does not fit what the site is considering. The BBC is considering the case where the conditional clause is talking about an expected or planned event in the future with a result in the past. "Tonight" in your example is talking about a future result. Furthermore, your conditional clause seems to be talking about habitual action rather than exclusively future action.
To fit into the model being discussed by the BBC, your example should be
If weren't getting up so early, I would have gone out for a drink last night.
And because you are discussing habitual action, you could alternatively say
If I didn't get up so early, I would have gone out for a drink last night.
The BBC example about the job interview is not a good example. It is not clear why someone could not have gone to a job interview yesterday because they were leaving on a holiday next week, but that is the situation being contemplated. The much more plausible situation of not being able to go to a future job interview due to a future holiday would be expressed as
If were not going on holiday next week, I could go to the job interview.
The wedding example is much better. Here it is quite easy to imagine why someone did not agree in the past to a future visit because it would conflict with a future wedding.
Does this help?