I should say as well, I managed to get drunk and corner a comedy producer recently. His advice was:
1) The industry wants more female writers (after the success of Miranda, there is a sudden drive for female-led scripts.)
However, they may not be much you can do about that. The second tip was:
2) Produce as much as you can yourself.
Remember, the great sitcoms of the 70s and 80s were shot using less technology than is in your phone.
Thanks for all the help guys, much obliged.
In your case and with your prior experience, I would suggest doing a dummy run and writing a script as an exercise.
Just something for yourself that you don't plan to show anyone. Ever.
Take one of your "B" or "C" ideas, rather than one of your best, and knock out a draft in a week, max.
It'll give you a feel for the process.
And you'll have your first script under your belt.
Better than feeling pressure to write your "masterpiece" right away.
You'll be surprised how much you'll learn from your first script. And writing your second script should feel less intimidating, and hopefully something you're dying to crack on with.