Clean, seal, de-mould large sky light window

Description Hello, we have skylight / window box (see photos, approx. dimensions L 250cm, W 100cm, H 80cm) which needs a very good clean and removal of mould. We also want to thoroughly check for air leaks and seal all areas possible with insulation tape. The ceiling is fairly high and the window is awkward to get to, so it hasn't been cleaned in a few years... we are now hoping to identify and eliminate any drafts as we believe it is causing the room to get v. cold. Your thoughts and suggestions for this will be welcome! The price will depend on you viewing the job and estimating how many hours it might take, you can let us know your typical hourly rate if that helps. Hoping to get this done in next 2 weeks if possible.