and like you, most people I talk to on the internet tend to think that my spoken english is on the same level as my written english. Wich is not true.
So, when people asks to meets in person, I'm quite reluctant.
A good way I've found, to introduce them to my spoken english is to, when someone asks if we should meet in real life,asks them if we could speak over skype (or any other software like it).
This might look like it's the same situation, but believe me, it's not, and that for several reasons :
Close to no Background noise
In a vocal conversation, background noise make understanting each other much harder. When both parties talk the same languages fluantly, it's not a problem, but when at least one of them does'nt talk fluantly, the background noise can hinder comprehension quite a bit.
Ability to write down to clarify a sentence
If the other person did not understand what you said, you can easily write your sentence to clarify what you means. Of course this is something you can do in person too, but writing on your phone, or on a notepad during a conversation is not usually well received.
Little to no effort required
If you decide to meet in person, both of you needs to decide of a place to meet up, probably something to do as well, and, if you planned something it might cost both of you money.
I believe that those factors matters a lot, if you plan something with somebody, and, on the spot, you realise that you can't communicate with that person efficiently, it can be frustrating.
On the other hand, if you talk over skype (or, again, any other relevant software), it doesn't cost any money, is almost effortless, and does'nt ask you to plan things in advance. If you realise you can't understand each other, it probably won't be as disappointing as if it happened in person.
A little piece of advice
Even if your spoken english is not all that good at the moment, I would encourage you to still try and hold conversations with other english-speaking peoples. After all "practice makes perfect" and the more you'll talk with other people (especially if they have a better level in english than you) the more you're going to learn.