I would do some further checking before assuming it is the head gasket leaking. Like Mike said, the oil will turn brown if it is getting coolant in it. Oil in the coolant is easy to spot too because it floats and you will see it in the coolant resorvoir.
I don't think a bad head gasket would cause the low oil light to come on. The sensor for the oil level is down on the side of the oil pan and could be an unrelated problem. If it is coming on and your oil level is okay, the level sensor might be bad.
I would suggest cleaning off the engine with some Castrol Purple and start it up and look very carefully at where the coolant is coming from. use a mirror if you have to. Look carefully along the head gasket seam (between the block and head) for coolant coming out.