Summer internships after having graduated?


Just wanted to know whether it’s realistic of trying to get on the Summer internship programmes after having actually graduated (from a Russell Group, top 10, 2.1 in Economics and Finance if that helps).

The reason for this is that I have an offer in Audit Big 4 for September 2013 and am worried applying for other actual graduate jobs could jeapordise this and run the risk of ending up with nothing. Is this unlikely?

I suppose an internship also has the benefit of seeing if I’m a “fit” for the IB world and whether I’d enjoy it once there…

Thanks in advance for any help!