Just from experience, you should have a meeting explaining the decision and you should have the opportunity to appeal after the selection is confirmed.
As above, what would you want to obtain from the case? Would you be likely to gain much more than the proposed redundancy package? If you find another job quickly, even if it was an unfair selection, the compensation might not be that much.
Be careful also that some solicitor might encourage you to raise an appeal without being clear on what you could really achieve. (Once again, just from personal experience).
Redundancy is difficult and it's easy to get angry and frustrated. So I would encourage you to step back, see what is on offer for you.