no, you do not always get it back when you apply for ILR.
but you are asked for it when you apply for citizenship, but i think there is a question on the citizenship app form, asking if you sent your cert for when you applied for ILR
but I've heard of a few cases where the person ticked the box, and was still asked for the Cert, and if you are asked for it, and don't have it....so get it photocopied, just in case, you wouldn't want to take it again
