settlement cracks extension single story

Hi, I am a new member here, in the process of buying a 3 bed 2 storey 1970's house and have noticed cracking in the masonry where the rear (single storey) extension meets the building. The cracks are stepped and go through both the bricks and the mortar. The extension itself is around 15 years...

in the summer (2017) we had a side extension built. Single story, it’s a garage, utility and bathroom. Since just before Christmas I have noticed cracks in the original parts of the house in all 3 bedrooms, including across the ceilings, the hall and staircase and kitchen. Most are hairline...