UK Immigration will not stop you if you havea one way ticket, as you're an EU citizen and the right to come to the UK is inherent of your citizenship. This applies to your kids as well.

 

You can enter with the German passaport without problems. Although, being a dual national you must depart from Venezuela with a Venezuelan passaport (Art. 7 Ley de Nacionalidad y Ciudadania). If you dont'n have one yet, well you know the rest of the history.

 

I find it hard to believe that being a dual citizenship holder, one must depart from a specific country versus a country of choice. Under general travel laws, one must possess a valid internationally recognized passport as a form of identification and entry requirements when travelling. I have never encountered an incident when one has to leave from a specific country because of citizenship.

If a person only has one passport, then that one passport is enough for travel anywhere, as long as it conforms to entry requirements of the country one wants to travel to (i.e. visas, permits), and of course, the passport should be valid and current.

Just my two cents....

 

In USA is required to produce a USA passport to enter o leave the country,even if you are a dual national. The following is copied from
http://www.fco.gov.uk/

"Some countries expect their dual nationals to travel on their national passports under certain circumstances. For example, the USA expects its dual nationals to use an American passport for travel to and from the United States. You should check with the authorities of your other nationality".

The same is applied in Venezuela. The hard part is to obtain a Venezuelan passport.

"Artículo 7. Los venezolanos y venezolanas que posean otra nacionalidad deberán hacer uso de la nacionalidad venezolana para su ingreso, permanencia y salida del territorio de la República, debiendo identificarse como tales en todos los actos civiles y políticos."