Should I learn Php to get into software development in my company? I'm a tester and already know python Django...

First: if you know Python and are automating stuff, you're already programming and developing software.

Second: if your company is a PHP shop, then you have 3 choices:

1. Learn PHP (it doesn't hurt to have another language in your toolbelt)
2. Try to convince your bosses that Python is a good solution for some stuff your company does (if it's the case). And by "convince" I mean: show numbers, build a small project that solves an actual problem, etc.
3. Find another company that is a Python shop and apply there. Be happy - and I would do it in this particular order. :D