Entitlement to statutory redundancy rights, namely a redundancy payment and protection against unfair dismissal (unfair selection for redundancy) is dependent on having the requisite continuous service. For redundancy payments it is two years' continuous service and for unfair dismissal it is 12 months' continuous service.
Continuity of employment is a statutory concept. The legislation states that a break of one week of service will break continuity. However there are some limited exceptions, one being absence from work in circumstances where it is customary for such absence to count for continuity.
If it could be shown, therefore, that absence on a career break constituted such circumstances, then you would be protected. Otherwise your break in service would make you ineligible.
Assuming you were eligible you could expect to be treated the same as if you were still at work.
Your employer would be expected to consult with you and your trade union in accordance with the appropriate statutory consultation provisions.
If your employer decided to select you for redundancy solely because you were on a career break this could be held to be unfair redundancy selection.
You would be entitled to appropriate statutory redundancy payments provided you had been continuously employed for two years or more and were over the age of 18.