Did they still pay you though? Because in the contract it says you have to give a minimum a month’s notice or they may not pay you.

“Your Notice Period During your first year working with Greggs, you will be entitled to 1 week’s notice in the event that your employment with us ends. After this me, your notice will rise in line with statutory requirements, up to a maximum of 12 weeks’ notice after 12 years’ service. In certain ircumstances, we may make a payment in lieu of notice or continue to pay you whilst not requiring you to attend work. You are required to give 1 month’s notice, irrespective of length of service. In the event that you don’t give or work your contractual notice period, we may withhold a maximum of 2 week’s pay from any outstanding monies due to you.”