Does your husband know of your intentions?
Have you been to some sort of "marriage guidance"?
I would certainly let you husband know of your intentions, as well as going to a solicitor.
Sadly divorces are often messy and strung out affairs, taking months or even years to sort out.
For example you say you have a 17 year old child, I assume living at home?.
Now you may think your husband will move out and you will stay in the house and be responsible for the 17 year old.
But your husband may say HE wants to stay in the house and look after the child and YOU will have to move out. And the court may agree, are you prepared for that?
Also once all the children have left home the house will probably have to be sold (if you own a house between you) and the proceeds split between both of you.
So you will then have to buy another house with your half of the money from the house. Are you prepared for that?.
So there are all sorts of things that may happen during the discussions for the divorce (money, property, child maintenance, access to the children etc etc).
I am not trying to talk you out of trying to get a divorce, but just letting you know that once you start the process it can get very nasty indeed.