Tax on FSAVC withdrawal

I have c£18k in a Free Standing AVC and I want to withdraw all of it in one go in the 2024/25 tax year. I have been told that HMRC will assume that this is a monthly withdrawal rather than a one off and will tax me on the basis of having an income of c£200k per annum. Is that really true and if so how do I claim the tax back? I will only have a self-employed income of less than £5k in that tax year.

Hi Jay Sear,
Please refer to:
Claim a tax refund when you've taken a small pension lump sum (P53)
Thank you.