Dipping into cold water is a brrrilliant and exhilarating experience - as long as you do it safely.
Before the swim
Practise! Turn your shower colder and colder to get used to the feeling. You only need to do it for a minute or two to start getting familiar with how it feels to be in cold water.
You can also practice in safe outdoor swimming spots such as Clevedon Marine Lake, West Country Water Park, or at the Portishead Open Air Pool ahead of the big dip. Portishead run cold water sessions in their unheated pool every weekend morning throughout November and their friendly team will be on hand to advise and support you.