I am looking to do a visa application for 2 members of staff at the London offices.

Hi there
Would I be able to apply for them if I have all the documentation as a representative, and if this is the case do I require a letter signed by them to clarify this. Also How long would the passports and documentation be with you for the visa to be issued, as one of the guys is going abroad next weekend and we need the visa for in approx 4 weeks time??