Can i join the paras even if im flat footed and ive got insoles

Flat feet often cause many problems, insoles should help but depending on the severity it may prevent you from joining. If you can pass the medical screening in the application stage and the doctor give you the go ahead then you should still be able to try out for the paras.

Is there a chance I could stop being flat footed if you know what I mean?

As far as i am aware you can not change the shape of your feet to not become flat footed. However your best bet for this answer would be to talk to a specialist and phone the recruitment centre and ask what the requirements are for this, this will also be picked up on your medical should you apply.

my flat feet are pretty mild and i dont experience any pain or discomfort or dificulties, i heard you can join if you dont have symptomatical flat feet