I have just received planning permission for an integrated garage conversion into a study and shower room. I’m adding an internal door to the hall way, bricking up and popping a window in where the existing garage door is and adding a small window at the side. I am completely ignorant. I have been told I need structural calculations from building control. I am a woman and I don’t want to be ripped off as I haven’t got a clue about these things. Does anyone have an idea of how much I should expect to pay for this please?