Generous early retirement schemes as an alternative to redundancy are much less common than they once were. This was one way in which employers used the big surpluses in schemes in the 1980s and 1990s to achieve their business objectives.
Few schemes have these large surpluses today. If you are offered early retirement as an incentive to accept voluntary redundancy, you should expect the full pension you have earned with no reduction for early retirement. There can be tax advantages in taking a lump sum of over £30,000 from a pension scheme rather than receiving it as redundancy pay.