Sorry for the late response, I hope this isn't too late for you!
There's obviously no point in asking if redundancy is the right option, it sounds like you made your decision ages ago from the above.
First things first, speak to HR and your manager! Talking to your employer is usually the easiest way to get the best outcome. Make it clear that you haven't made a decision as yet but you would like as much information as possible to make that decision and find out what the redundancy package is, asking some questions about the new role first will help to show that you're not just trying to find out what they'll offer. If it's a good package then take it and run. A reasonable package seems to be 1 month for every complete year you've worked PLUS your notice period (although you're often expected to continue in the job if they pay your notice), however they do vary greatly and the minimum legal is a pitance!
If the redundancy package isn't great you'll want to google the term "working under protest", it's basically when your job significantly changes you can notify your employer that you're continuing to work but that you don't agree with the changes and will likely be taking legal action along unfair dismissal lines. I'm not saying you should go down that route (the legal route is a pain), however understanding what it means is useful. For example, if they offer you a really bad redundancy package you can try and negotiate, e.g: "So my options are a) to take a role where the objectives seem impossible to achieve, accept a redundancy package which currently doesn't make it worth my while considering as I have a wife/family/home/350Z to support or c) work under protest while seeking external legal advice which I'm sure neither of us want to waste time/money on, is there anything that can be changed to improve a or b?". Bear in mind that they only legally have to pay you the mimimum statutory redundancy though so you want to be polite and don't want to push too far unless you've made the decision to go regardless.