Tax Treatment of Pension Contributions for Non-Residents

I have a salary sacrifice occupational pension to which my company also contributes. I am a UK non-resident and do very limited time back in the UK so have very low relevant UK earnings. I am still entitled to contribute to my pension as I am a relevant UK individual. I am in the process of completing three tax returns, as I had tax deducted at source through PAYE for which I need to claim a refund. When I complete my tax return, I intend to gross up my taxable earnings by my salary sacrifice contributions and then back out foreign income not taxable in the UK in box 12 on page Ai2. By taking this approach I am effectively removing any chance of tax relief on my pension contributions. As for my employer's contributions these are irrelevant to my tax position so will be ignored on my self assessment. Is this approach appropriate?

Hi,
If you do that, you will not receive any tax relief up to the basic amount of £3600.  
Any pension payments in excess of this sum will be subject to pension savings tax charges and should be declared in box 10 of SA101 page Ai4.
Thank you.

That can't be right - as by grossing up my salary, I'm in effect not making pension contributions - and as you say, I'm not not receiving any tax relief and the only rationale for the pension savings tax charge is to repay tax I would otherwise pay as a UK taxpayer, and what you're suggesting would mean I would be taxed on the income (because I'm not receiving pension tax relief) and then I'd be taxed on it again through the pension savings tax charge.