A trick I use with questionable fish is to soak the fillet in milk after it thaws for 20 min to 2 hours. Pat it dry and glaze/season. It usually takes any “fishyness” smell/flavor out of it.
In the US there are some things covered in the survey and some not. We paid for an independent home inspector to go top to bottom of ours before purchase. I tested the water, had the most recent electrician go over our system, and talked to the neighbors about the history of the property. It was very good to have all that information and worth the money to pay for. It greatly reduced the worry and I got to know the property before buying it.
dive into the world of old school drafting supplies…oh man, I used to draft scale artistic renderings of houses on vellum. Look up “Drafting Machine” and accessories. Just beautiful, super accurate equipment back in the day.