Help with declaring tax on foreign income

Hi there, I'm a UK resident and I'm mainly employed by a UK company. Last year, I did a one-off piece of work with a company in Poland. This was all done remotely and I remained resident in the UK - I was paid into my UK bank account. My pay was taxed in Poland and I have a document from the Polish company that I think is the same as a P45. I just want to check that I'm declaring this income correctly... 1. Should I add the Polish company as an 'employer' on my tax return, where I declare my other UK employment (even though they don't have a PAYE tax reference?) 2. Could I check what I put in the 'Pay before tax taken off' box? My 'P45' from the company shows my total pay *before* Polish tax was deducted, in Zloty. I believe I should use a currency converter to calculate the pay in GBP, using the exchange rate at the time of payment, and declare that - is that correct? Or, do I show the pay I received *after* Polish tax was taken off (but before UK tax was taken, obviously)? 3. Am I right in thinking that it is the same number as in Question 2 that I then put in the 'Foreign Tax' section where it asks for 'Taxable amount'? ("Enter the gross amount of income, before any tax has been taken off, which you reported elsewhere and on which foreign tax has been paid.") 4. About currency conversion: what date do I use for the rates? The date it arrived in my bank account, or the date on the document from the company (which is several months after the payment was made), or something else? 5. About tax relief on the Polish tax paid: what date do I use for the currency conversion rates there? Any help much appreciated!

Hi,
Please refer to guidance at Tax on foreign income If you're taxed twice
Thank you.