“the applicant’s pre-action letter dated5 December 2024 did not seek to challenge a delay in processing his visa application. Instead, the pre-action letter challenged the refusal of his application. In contrast, the judicial review claim form challenges the respondent’s purported unlawful delay in making a new decision on that application. Therefore, the pre-action letter of5 December 2024 did not foreshadow the basis of the judicial review claim”