I would counter argue the selection process is already unfair as they have only identified me to be at risk when I am part of a team all doing the same thing. I understand what you are saying that they have not actually made me redundant yet but as the only one identified as at risk, that puts me at the front of the queue and is fundamentally unfair.
But not in law it isn't. The point of consultation is for both sides to listen to what the other has to say. You have decided it is unfair (and I agree here is possibly good cause for that) but you have not heard why they think this; and they haven't heard why you think it is unfair, so they have had no opportunity to consider alternatives. "Unfair" and "unfair in law" are very different things.
My old employer will take me back at any point so I will let the process run its course before going back, although securing new employment does not mean there is no unfair dismissal, it just means any compensation will be lower as there are no income worries.
You have a job offer. If they find out - and that could even include if the question came up at a tribunal - then yes, it actually can mean that you cannot claim unfair dismissal because you are "setting them up" when you have no intention of staying anyway because you have another job.
I don't disagree with anything you are saying, simply urging that you cool down and don't make decisions based purely on anger. Being selected for being at risk and being made redundant, or even remaining as the only one made redundant might be unfair but the law is far more complicated than that, and stacked with the employer. As both a manager and a trade unionist I can tell you with absolute certainty that you currently have NO case, despite what you may have been told, because a case is determined on the end facts, not the beginning facts. I can also tell you with certainty that any employer worth a spit can still spin this as entirely fair in law - because I could based solely on what you have already told us, and a bit of the "inspired thinking" that employers use to justify decisions that aren't justifiable.
As I said, personally I'd accept the other job and then be ill for the rest of my notice period because that is the line of least resistance, providing your former employer is "in the bag". Or they might just pay you something to go quietly if you hang on and argue. But do remember that employment tribunals are lengthy coming around, time consuming, stressful, and risky, and so you will be using up your free time for a long time to come still living with this anger; and that isn't healthy. But in the end it is your decision obviously - just be realistic that it will come at a cost to you, and even if you win, you may not feel any better about it.