30 M Starting Swimming, any tips?

Hi Guys, I have been suffering from disc bulges for the past 18months, I have left over nerve damage and numbness in my left leg and a little in my right leg. My pain clinic has advised me to take up swimming 3 times a week as it is not weight-bearing, and post-injury, I have gained some body fat and have struggled to get back into weight training.

My question is: I have been active for years before the injury and can swim in the open sea on holiday, but can you provide me with any tips for swimming techniques I can learn when I get back in the water?

My DMs are also open. Thanks, guys!