@Tod ********
confirmed, I had no problem with visa - if you initially say you intend to stay 90 days it directs you to apply for a 60 day visa and there is even a pop up telling you that you can apply for a 30 extension.
I had no problem checking in at Manchester.
To be on the safe side I would take a screen shot of the actual visa application to show at check in.
There is anecdotal evidence however in the US airlines have demanded a return within 60 days.