You can see the amount you've paid in your transaction history on your Penfold dashboard. Please remember that if you have contributed into any other pension - separate to Penfold - you will also have to take add these contributions on if this is for your self assessment tax return.
You will also need to declare how much tax relief that you've received on top of these contributions. You can do this by:
Taking your total amount paid into your pension and multiplying it by 1.25
For example, you paid in £600, multiply this by 1.25 = £750. That is how much you would need to declare in your tax return