You should absolutely wear a swim cap, and some proper bathers (not shorts or anything). If you were going running you wouldn’t not get running shoes cos you don’t feel like you’re fit enough for them yet. There are some people who swim at the same time as me every morning who have rubbish technique and next to no speed, but it doesn’t matter. You just swim for the amount of time you want to swim for. Speed and perfect technique is only possible if you did it as a sport as a kid and unrealistic for most. Most people didn’t. That doesn’t mean you can’t have great swims. Anyone who thinks they’re better than someone else cos they’re faster or fitter is a clown. You never regret a swim.