Results Day: 16th August - Can't get much more important than that.
Edexcel Results Plus: Can access your Edexcel results on the morning of results day (only if you have been given a PIN by your school).
UCAS site: May update whether you have been accepted or rejected by a university earlier in the morning, though it may not. Difficulties in accessing the page have also been reported due to the large number of people accessing it.
It is generally a good idea to go into school to pick up results anyway, in case of needing to sort things out with teachers etc.
If you are away on results day, how you recieve your results depends on your school/college; some will allow friends to pick them up for you, some will call you and some will arrange to send the letter to a different address among other methods. Check with your school.
Just a few things of the top of my head; i'm sure there will be many more questions.