As you say, it is really important to think about your 'why' - why do you want to read Shakespeare, specifically? (You have answered some of this above). It's going to be difficult for you to read Shakespeare/ Dickens for pleasure if you don't actually get pleasure out of reading them.
If you just want a good story... well, there are lots of modern stories out there which are just as good, to be honest, and won't give you the kind of distress you're currently experiencing with the archaic language.
And with Shakespeare, the story isn't really the reason he is so famous and renowned. His stories are actually very simple. It's the language itself, and it sounds like that is the bit you're struggling with (as many people do!)
So ask yourself if you want to understand the language? Is that something you care about/ will enjoy/ get some satisfaction from?
If so, then yes, the thing to do is to find a summary of the story so that you understand the basic gist of what's going on. But then, you need to sit down with the original text and get yourself a study guide, and read them together, so that you can decode and understand the language.
If you don't do the second step, then honestly, you might as well read a better story written by a modern author :)
You say you want to do it for pleasure, and for some people decoding archaic language is just not pleasurable, and there's nothing wrong with that.
You don't need to read Shakespeare - you can just find other stories that you will get pleasure from.
But if this is pleasurable for you then go for it!