As soon as possible : a written request does not sit waiting. At deadline time or in an emergency, call the office — that is the most direct way to get an answer.
Purchase and sales invoices for the period, bank statements, current contracts and, if you have staff, the payroll details. Paper or digital, it makes no difference — I send you the exact list before every deadline.
Yes, both residents and non-residents. Foreign-source income, double taxation treaties, tax assimilation and annual adjustment requests are a regular part of the practice's work.
Yes, at any time. I collect the file from your previous accountant, pick up the trial balance at the handover date and check the returns already filed. There is nothing for you to do yourself.
A first meeting, with no commitment.
You set out your situation, I tell you what it actually means in terms of time and obligations. Reply as soon as possible.