There is no formal mid-year review. However, you can access a copy of the appraisal at any time during the year via self-service and update your objective progress throughout the year. For example, if you complete an objective early, you can make a note of this. If you have any concerns regarding the objectives, or require any additional support, you should raise this with your line manager.
You may wish to include comments relating to exceptional achievements which were not included within the initial objectives set for the year. This should be noted in the final comment section at the end of the appraisal document.