Just hold him the whole time, Tanya When going in, hold him with his back against your chest, with your arm around his chest so that he floats from bum up when you enter. Use floaties when he's more comfy in depth of the pool and can move more independently in it. You can do a few things - float him on his back, swish him around on his front, facing you and get his face wet.
You also don't need all the UV stuff if you're in an indoor pool, just a swim nappy of some description. It's probably best if they can feel the water on their bodies before you start to cover them up.
Most of all, smile lots and make sure he is far enough away from your face so that he can focus on your positive expressions!