Identity and civil documents for every intended applicant, a full immigration and travel history, records addressing any admissibility question, and a written confirmation of the current programme terms taken from official sources on that date. Where a company is sponsoring, its written commitment covering which fees and gifts it will pay.
The fee is not refundable, so the file should be ready before it is paid
A nonrefundable payment reverses the usual order of preparation. Rather than paying to begin and assembling afterwards, an applicant is better served by having the household's documents in order first: passports for everyone intended to accompany, civil documents proving each relationship, and certified translations of anything not in English. A candid history of previous applications, refusals, overstays or removals matters more here than in a route where a refusal simply ends the matter, because admissibility questions do not disappear because a fee has been paid.
Where a corporate sponsor is involved, the offer should be reduced to writing and should say plainly which payments the company makes, which remain personal, and what happens if the employment relationship ends. Finally, the official terms should be printed on the day and kept, so that later discussion rests on what was published rather than on recollection.