Rossles

Hi all Scottish self builders, I am in the planning process of a self build project, plot is north of Inverness. Architect is currently finalizing detailed drawings to submit for building warrant. I am keen to know from other self builders, how much Tax I will be liable to pay - both Second home Tax and / or Stamp duty? I am planning on keeping my current property. Really can't find much information online. I'm sure a mortgage advisor will put me right but thought I would ask here. I am also interested in who knows what the average cost estimate is per m2 in the North east currently?I am building a 1.5 storey +- 250 m2. Any knowledge or advice would be warmly welcomed.