I'm a resitter, and it was the best thing I ever did.
2010 AS
Chem - E
Maths - D
English - C
Bio - C
2011 AS
Maths - A
English - A
Finance - A
Politics - B
Got accepted into Sheffield, Lancaster, Loughboro and Reading.
And could have probably got into better unis too but they didn't do the course I wanted. Being a re-sitter isn't too bad unless you're applying to the up themselves unis like Imperial or something.