To enter the UK under my visa category, it is highly recommended that you have a return ticket. However, the dates for my final exams vary widely and aren't announced until after I arrive in January. Therefore, I need to book a one way ticket from Manchester, UK to the Minneapolis-Saint Paul area that is either flexible or fully refundable. Does anyone have any experience in booking tickets like this? I'm wondering if it's possible to book online or if I need to call a specific airline. I need around a 2-3 week flex (leaving roughly anytime between June 10-July 1) or a fully refundable ticket.

Thanks for your help.