Your artwork is easily of the quality that most students have when they finish the Guildhall and many of them started with way less experience. The art professors, the Walker brothers, there are amazing and if you really wanted someone to push you further they'd be the people to do it. You'd also get a lot of exposure to the video game industry and get a feel of what working in it would be like. Alternatively you could skip it entirely and start applying to get a job when you're finished with college. I think you'd be sucessful with either option.