Real Estate / Anyone converted a shed/garage into a home and can shed some light if this is possible? [4]

Hi
I married a polish man, whom I share 2 young children with. We regularly visit Poland, we live in the uk, and was looking to buy a small holiday home as we want our children to learn the language, culture and be around polish family. The house would have also served as our retirement home as we plan to retire there as we love it there.

My mother in law has a large shed with attached garage. We'd guess it has a total size of around 60 square metres. She has said we can convert this into our home to stay close to family and reduce costs. It doesn't have heating or plumbing, just very basic electrics.

Just wondering whether anyone has done anything similar? How strict are rules about converting these types of buildings into homes? How strict are building regulations and if anyone can direct me to any useful information regarding this I'd really appreciate it.

Thanks for taking the time to read and help 😊