Tengo que ir andando
Heard and reinterpreted from a Porteguese episode of Law and Order. Can "tengo que ir andando" mean I've got to get going?
Fun fact/grammar point. Most people know about ir + a + an infinitive, such as voy a leer, I'm going to read. However, you can use a similar formula, ir + gerund (-ando/-iendo) to mean something slowly or gradually happening. Voy leyendo este libro = I'm gradually reading this book. I must note that it should only be used with things that are capable of being completed, as my Spanish friend said it sounds a bit awkward to say "Voy aprendiendo español". You can't finish learning a language.
I am going to answer this thread just in case another incorrect answer gets accepted, this is incorrect, you cannot say that.
Tengo que ir andando: I have to go walking
Tengo que apañarmelas, tengo que seguir con mi vida...I have to go on.
I haven't heard this particular phrase used, but just a thought....it strikes me as meaning, "I have to go on". (in the sense of moving on). What was the context?
Voy en el coche de San Fernando, un ratito a pie y otro andando....
Yes. Andando generally means kind of wandering around, just going someplace in general.