Yes, do as the above 2 suggest.
CAB should tell you that your employer cannot just change your contract in this manner. Changes must be by negotiation and they must give you at least 5 weeks notice of the proposed change.
You are not entitled to redundancy (because your job is not redundant - quite the reverse) - but ask CAB about resigning and claiming constructive dismissal. This is not to be taken lightly, but if you are looking to be 'out' anyway, it could provide you with money. It involves taking your case to an Employment Tribunal.