My first visit was in July for a conference that lasted 3 days, and because I had school and work to come back to, I returned to my home country without having visited any of the places I wanted to visit in the UK. My visa was granted on the basis of the invitation to the conference, and the organizers arranged my accommodation as well. I am going back in October during a 10-day vacation, and I will be staying with my mum's cousin in Luton during that time. I will be carrying an updated Certificate of No Objection from work and Proof of Studentship from my school.
My question is, do I need a letter from my mum's cousin stating that I'll be staying with them during this time since I don't have a hotel booking? Is there any other document I should expect to be asked of me by border control?
It may be important to note I did not mention any family in the UK when I initially applied for my visa.