can you change the amount of maintenance loan you get?

I might keep my weekend job that I currently have at home at work there in summer and Christmas so I won't need such a large loan but my managers aren't sure yet if I can do that and ill only find out in September when they ask head office. Without i'll probably need around £8k (London) with the job ill only need £2k so I'm not sure what to do. Also should I apply for housing for my firm and back up?