Info wedding (Jakarta)

Hi all I'm about to marry my girlfrend and we would like to do it in September for that I'm going there for 20days. I've read and so far find out what kind of document I need but I've got some issues with some of them first about the change of religion to Islam how that work and how long it takes? Also about the no impediment letter from the ambassy what kind of document I need and how long it takes:S
My worry Is that I might not do all in time so if anyone know about it or experienced that as well and would like to share pls do:)
Abt me I'm Italian but resident in the uk also If all goes ok for the eea family visa would it be fine to get it cause physically we will be togher a month but we know from more than 1 and half year .
Thanks I'm advance to all! :)