Moussemoose please don't worry about small things like what to do. The fact that you're making the effort to go will be appreciated.
My experience is of Egypt and this is what it is like where I was. It is probably quite different to what happens in the UK and there is a lots of diversity in practice.
After the death, the body is washed in a ritualised way. This is performed by the women of the family if the deceased is a woman or the men if the deceased is male. The funeral and burial are performed as soon as possible afterwards and the burial should occur during daylight hours.
The janaza (funeral prayer) is performed differently to normal prayers but often directly after them, so everyone prays the noon prayer and then the funeral prayer. The women participate in the prayer but in their own section.
Directly after the prayers the men depart to bury the body. Normally only men do this.
In Egypt the time to pay respects is usually at the house of the deceased or in a specially erected funeral tent for three days after the death. This is called the "azza". There will be a sombre atmosphere with Qur'an reading and supplications for the deceased, as well as talking and being together.
I don't think there is much to worry about regarding colour. White is a mourning colour in many Islamic countries. In Egypt there is no specific colour for men, but women wear black and in the case of family this would last for 40 days, for widows often longer. I think that this is a pre-Islamic custom specific to Egypt however as Muslims and Christians do this.