I'm not clear on your exact situation from your original post. Am I correct in saying that your employer is changing both the hours in which you work and has also imposed paycuts?. If this is the case, and you have not agreed to both of these, then they are changing the terms and conditions of your employment without your agreement and this may give you grounds to bring a claim of unfair dismissal against your employer.
At this stage, I would not suggest you resign, instead I suggest you arrange an appointment at your local citizens advice bureau and see what they say.