wouldnt worry about a thing , the pointing on the brickwork has just popped due to frost and not grinding the old cement out just faking it over the top of the old cement , keep an eye on the crack not major at all no under pinning required or structual engineer needed at that stage , 18 " of concrete ample , any house of the age of and onwards would have been built off clay , nowt to worry about ,atb ryhope toma