Four things, done properly

What a power of attorney does, when you need one, the wording that matters, and how it gets certified and legalised for use abroad.

What certified means in the UK, which documents need it, how certification differs from notarisation, and what makes a translation get refused.

What an apostille is, which documents can carry one, the route for non-Hague countries, and the sequencing mistakes that cost the most time.

Which records can be obtained from the UK, how a request is made on your behalf, and what turns a certificate into a document an authority accepts.