It all depends on your contract really. If your contract says that are based at the original address then that is your permanent place of work and any additional miles to another can be claimed from the company if the change is only temporary. If the change is permanent and your contract states you are based at the original, then you can either refuse the request or ask for a raise to cover the additional travel costs.

By law they have to then either give you the raise or compensate you in some other way, if you refuse to move and they sack you then you can take them to court for unfair dismissal.

As to lowering your wages then unless the job has changed considerably, ie less hours, diffrent work etc then they should not be lowering your salary.

Best thing to do would be to speak to your manager and HR department or failing that the local Citizen's Advice Bureau.