Usually, as long as it has the right visa and the required documents, the international students will not have problems in immigration. However, just in case, you should keep your University telephone number available if you need help from the University to clarify matters with the immigration authorities. Meanwhile, you can also take the English exam for getting UK visa at Trinity selt.
If the immigration officer feels your document is incomplete, you can seek help at a foreign student advisory center at your university. If you do not have complete documents, you will be refused entry by UK Immigration. Depending on the case, you may be given one or two months to leave or enter the UK.
Sometimes you may experience unpleasant situations such as airplane delay or baggage loss. Stay calm and do not panic, ask the friendly airport staff to help you. Panicking in this kind of a scenario is the last thing that you want to do, so keeping yourself calm and put your trust in the people who can be contacted there can be a wise decision.