Assessment at Oxford is challenging but nothing impossible. Its a realistic airline interview process, but obviously it takes into account that you have no flying experience! If you go to the Oxford forums themselves that is a lot of information on the process and about the school etc. I think the link is on the main Oxford website!
One thing to add, before actually starting one of these courses its probably a good idea to have some lessons at your local flying school. Just so you know what its like. Once you've flown and decide that you do want to follow the dream then you need to get your class 1 medical to see if you actually CAN follow it!