I understand that you are only ‘fined’ or whatever if your second tax return is late - apparently the tax authorities are not surprised if new arrivals don’t manage to file on time. I can’t remember where I read this but know I have seen it more than once.
I have a Paypal account number! I logged into my account and looked at settings. Top left it shows the year I opened my account but no date besides that. I clicked on Data and Privacy at the top and was given an option to download my data. I chose Credit Information (although it turns out I hadn’t asked for credit). I had to wait for a response (it said it may take 30 days but it took less than 24 hours in my case) and was sent a pdf which included personal details and a 19 digit account number. So much for them saying you don’t have an account number.
I am using ecb.europe.eu website to calculate the exchange rate. It gives daily rates - okay for this year as I only have December 2020 to declare may prove more difficult next year.