If your email items and calendar items appear to have a time offset, it is most likely due to having the wrong time zone or region set. Follow the below steps to alter these settings to UK time:
Step 1: Login to Outlook Web Access
Step 2: Click Settings, and then click Options.
Step3: In the left navigation pane, click Settings, and then click Regional.
Step4: In the Current time zone box, click the arrow, and then click the correct time zone setting.
Step 5: Click Save.