I'm in the same boat as you.
My self-cut sim is also stuck inside my iPad2.
Luckily it is working so no problems at this stage.
I've done a lot of reading(www) and there does not seem to be an easy solution.
I phoned a place in CT and they claimed that they might be able to remove it - alternatively they would have to open the iPad to remove it(that was not an option for me).
Can you see anything at all? If so, can you get some tweezers in? Or else you might have to drill a hole in the sim (suggest 0,4mm) and insert a reverse thread bit in and pull it out.