Let me take a look at this and I''l get back to you in a short while.
You should refer to sections 5 and 9 of RDR1 here which explain domicile and the remittance basis of assessment respectively.
As you appear to be non-UK domiciled, you have three choices as to how you are taxed in the UK on non-UK income and capital gains:
1 If the non-UK income and capital gains is less than £2,000 in any one UK tax year, then you need not report it to HMRC in the UK and need only report non-UK income and gains you bring into the UK which you would pay UK tax on with credit being given for tax paid on the same income and gains in Argentina against the UK tax liability.
2 1 If the non-UK income and capital gains is £2,000 or more in any one UK tax year, then you need to make a claim for the remittance basis to apply so that you don't pay UK tax on non-UK income and gains you don't bring into the UK. You would still report non-UK income and gains you bring into the UK which you would pay UK tax on with credit being given for tax paid on the same income and gains in Argentina against the UK tax liability.
3 You can choose to be taxed on your worldwide income and gains as a UK domiciled individual who is resident in the UK does.
You are allowed to bring into the UK savings you had immediately before you came to the UK and pay no UK tax on them so you would need to work out what that sum was and be able to prove it if necessary.
I hope this helps but let me know if you have any further questions.
Inheritances aren't taxable in the UK so you can bring that into the UK tax free. If you had earned any income from it after your arrival in the UK, then that may have been taxable depending on how much it was.
If you sell your home in Argentina and bring the gain (the sale proceeds less purchase price or value at the time you inherited it in your case) into the UK that may be liable to CGT in the UK. Take a look at HS283 here for information on the main residence and CGT. If it was your main home from when you inherited it until you came to Europe two years ago, most of the gain will be tax free. You are given the last 18 months of ownership as a tax free period in addition to the period when you lived in it.
If the disposal proceeds of the flat are more than £44,400 and/or the gain is more than £11,100 (the tax free amount of capital gains you can make in a tax year) then you need to report it along with your income in a self-assessment tax return for the tax year in which you sell it. You can register for self-assessment using a form SA1. You would not need to report the cash you inherited as that won't have grown in the safe box.
I'm just following up to find out if my answer helped or if you have any further questions