you can switch to a masters after a year - you would normally write a 1st year report and then continue onto year 2, but this can be used as a masters thesis instead (you would probably be awarded an mphil). obviously the regulations differ from uni to uni, the best thing to do would be to talk to your supervisor. do they think you should continue with a phd? is your work of a high enough standard to be used as a masters dissertation? (no offence intended here, but 6 months into a phd project you wouldn't have expected to achieve a great deal, whereas 6 months into a masters project you would be halfway through and som things would have moved along a bit quicker). you need to speak to someone at your uni who can advise you as to the best course of action from here.