First of all did you convert for your girl? If you did and you pretend to be more religious than you actually are to save face in front of the "community" you will earn brownie points with the family. It will soften the blow of their daughter marrying a "gora". I had a similar family drama when my sister brought home a black guy, the shit hit the fan. And my brother married a white girl from Canada in January so I have had all sorts of experience with this. MY parents are super traditional and quite religious and at the end of the day they just want us to be married to muslims regardless of color. Hopefully her parents are the same way. If they try to really object to you marrying your girlfriend just come at them from a religious standpoint about how islamically they have no right to stop you form marrying her if you converted.
now as far as learning urdu. I find it ridiculous she doesnt have the time to teach you but maybe you can learn after you are married. I have A LOT of friends who married white/hispanic/black Americans and after a few years of living together the guys speak better urdu than me sometimes.

When you meet her family greet them with a salam and that will go a long way into them accepting you.

Also hindi and urdu are not as simialr as some people here are telling you. What you see in a bollywood movie is not really hindi its a mixture or urdu and hindi so they can have a bigger audience all over Asia. Im not sure a language program for hindi will even teach you bollywood hindi as opposed to actual hardcore hindi. And i bet you 500 buck your girl doesnt even know how to read or write urdu (very few of us here do) so just focus on speaking it and not reading it.

But like Anjum said, you are in for some major drama so good luck with that shit!