Can someone help me with employment law on contracts ?
A contract does not have to be in writing under Uk employment law. The fact that your employer verbally agreed to this shift pattern and that this shift pattern has prevailed for 15 mths is sufficient to constitute a contract. If they now want to alter that, they have to consult you, although ultimately if you dont agree to a change of contract they wuld have to take disciplinary and ultimately dismiss you.