If you decide you will be unable to complete your project and coursework within your registration period, for valid (usually personal) reasons, you should discuss your situation with the Programme Manager in the first instance, and perhaps consider taking a 'withdrawal' from your course.
The Board of Examiners can recommend awards of Postgraduate Certificate or Postgraduate Award (for which no project is required) for students who have permanently withdrawn from the course (and have the appropriate number and combination of module passes). If the Board of Examiners then recommends this award, you may have the option of re-applying at a later date (usually within 2 years) to return to complete the MSc and carry forward credits completed in a 5-year window prior to your return.
The Board of Examiners may award the Postgraduate Diploma, Postgraduate Certificate or Postgraduate Award to candidates who do not complete the MSc. However if you have completed the full year and simply did not complete the associated work, the Department is unlikely to support any application to return with credit to complete the MSc.