Written notice is not legally required (unless the company is a large one and there are collective redundancies being announced), unless this is specified in your contract (which it rarely is). If you would like it in writing, it is best to write to the employer asking for written confirmation, which he should provide (if he doesn't want to leave himself open to possible unfair dismissal proceedings).
If you have more than 2 years service, then once you are made redundant your employer does however have to issue an RP50 form to you confirming the fact that the reason for the termination of your employment was redundancy.