What you're suffering from isn't a block it's fear and insecurity. You're scared of failing so you're intimidated by the tablet, or even getting started. When you do get started your insecurities well up and begin to push that little button called performance anxiety.
Acknowledging and knowing the things that keep you from creating is the best way to push past them. Setting realistic goals (as in not aiming too high) is what's going to give you a good start to your work. Don't begin with a giant epic or comedy with a huge cast of characters. Start small. Begin with something easy that you enjoy drawing.
I love dogs. I drew dogs for years. I did a little comic years ago about a dog and it's everyday adventures being a derpy little dog. it wasn't my best work, but it got me started and helped me build confidence to do something more complex.
You cannot get better if you don't finish anything. So start on a SIMPLE and SHORT comic. Make working on it a habit. Schedule time during the week, even if it's only two hours, as your set "comic" time.
Create a ritual for yourself to keep you going and get you in the right headspace. Maybe you work better at night? So change into your PJ's, put on some music (seriously, music or podcasts ONLY anything more than that will just be a distraction), and settle into work. Personally, I use a candle and incense. I strike a match, light a tea light and then light the incense. I only use a specific incense for my creative time. I do not use it any other time. The smell sets my mind to focus on the task in front of me, and snaps my brain into "work" mode. You can use music to do the same thing, for example only listening to a certain musician or type of music only when you're working.
I hope you get started on your projects soon. Only you can tell the stories you have to share and I look forward to seeing them. 