CO doesn't offer complimentary upgrades on BusinessFirst serviced flights (EWR-London is a BF serviced flight). The only way to get into the front cabin is to purchase an upgradeable fare (H, K, or Y) and then use miles to upgrade. Seats may or may not be available for upgrade. Generally seats are not available for upgrade using miles until 30 days prior to the flight. For more information use the search function at the top of the page and use the search term "HoKeY" and you will find a wealth of info on this topic.