Contract terms
A. Almost certainly not. Even though you didn’t sign the new contract terms, by taking advantage of the pay rise and better holiday, you would normally expect a tribunal to find that you accepted the new contract, including the less favourable redundancy terms.
The tribunal would say that the only sensible explanation for your behaviour — taking advantage of the benefits of the new contract such as the extra holiday — is that you accepted all the terms of the new contract, good and bad, whether or not you signed it.
A tribunal would not be interested in what you privately intended or thought about the new contract. Instead, it would look only at how your behaviour — taking the benefits of the new contract without protest — looks to an objective outsider.
If the only sensible explanation is that you intended to accept the new contract terms, then you will be bound, meaning you’ve lost the right to the more favourable redundancy package.