UK/TURKEY DOUBLE TAXATION AGREEMENT
Subject to the provisions of paragraph (2) of Article 19 of this Agreement, pensions and other similar remuneration paid in consideration of past employment and any payments made under the social security scheme of either Contracting State, and annuities as defined in paragraph (2) of this Article, shall be taxable only in the State of which the recipient is a resident.
From which I understand that HMRC would not get involved in your pension earnings once you have retired to Turkey (and become resident)
Do the Turkish tax authorites get involved ?