I thought you already created a thread about this…anyway…
Most gyms provide free assessments, often to sell you personal training packages, and I think paying a personal trainer for a few to several sessions to learn proper form and set up a routine is definitely the way to go. There are also a lot of YouTube trainers from which you can learn good form (many RJ members recommend Scott Herman, presumably because he's young, blonde and cute; I personally like Vic Costa).
There are a million diets out there but you've read enough threads on healthy eating to know what that means - several small meals/snacks a day with smaller portion sizes, cutting processed food, limiting unhealthy carbs and fats, avoiding sugar. I could inundate you with minutia but that's no way to start - you'll enjoy easy beginner results first, then in a few months when you're more confident fine tune/dial in after you've transitioned into a healthier lifestyle.
Two final thoughts:
1) Don't be intimidated by gyms, gay or straight - no one's going to be looking at you, they're too busy looking at THEMSELVES.
2) Don't overdo "Biggest Loser" style. That's the fast track to injury and demotivation.