Dear Adele
Why do we do it?   We try and cover every scenario and then it doesn’t happen as we thought, what then?
Let’s look at each of your concerns.  You are not confident, yet, that you have the proper coping skills to deal with your CG.    There is no badge or medal to show you have come top of the class in confidence – if there was I wouldn’t have it yet.   You are ‘aware’ of your husband’s addiction in a way you have never been before – that awareness is ‘in’ you now and whatever you do it will work for you.  
You don’t think he understands things are changing for you but he can’t ‘understand’ because the changes in you are not visual.   His behaviour will hopefully react to your change but he won’t notice it as he would a new hair style.   He can’t see you climbing into the driving seat and putting his addiction under serious threat. 
Worse still he ‘will’ have noticed changes in you and be scared you are leaving him.   – He is an active CG whose prior interest, above any grandchildren or life that ‘you’ think he should care about most, is the next gamble.   ‘If’ he tries the emotional ********* then your new found confidence that ‘really is there’ will not be so easily fooled.   Active CGs weep because they are afraid that time is being called on their addiction.   Non-CGs are suckers for tears and how the addiction knows it.   The addiction to gamble produces crocodile tears.  We try to believe the loved one shares ‘our’ emotions, we want the tears to be real but the loved one’s addiction has one motivation and that is to satisfy it’s craving – it cries only for itself. 
I am sure your husband will enjoy fresh clothes and all the things that are important to you but they are mere trappings to an active CG.   You will exude the difference in you – you don’t need to make things clear to him.   Nobody can ‘make’ a CG see things clearly unless they want to see.  
If he didn’t behave as though nothing has happened it would be surprising.   CGs do behave as though past behaviour has not happened – it is symptomatic of the addiction.   If he did behave as though something has happened then he would be moving towards accepting his addiction.  You are ready for this Adele.   You are as ready as any of us would ever be at the stage you are at.  
I understand you miss him – but you miss the man, not his addiction.   Unfortunately until he determines to change, the two things are inter-twined.   It is the addiction you are fighting not the man you love and you are fighting it because you love him.  
The ‘only’ concern I have in your post is that you say you are not sure you ‘want’ to deal with his addiction just yet.   I understand this.   It is messy and if you can put it off maybe things will just change without any effort.  I put it off for 25 years so I can’t judge – but there never will be a right time.   You have started taking over the driving, if you slump back into the passenger seat allowing him to drive on recklessly then his addiction will be right there beside you.  
I cannot tell you what to do (as you know) but I think you should stop worrying about what if this and what if that.   You will have changed whether you wanted to or not.  I can’t go back to the unwitting innocent that I was anymore than you can – we can’t undo what we know and we try and forget at our peril.  
There is no need for rows or ultimatums that have no effect anyway.  Be yourself when he comes home and allow the knowledge (and confidence) that you do have carry you through.  I have read your post to BB – you meant what you were saying – you are ready, you are strong.   If the visit does result in the neutral chit chat, then so be it, we can talk about it afterwards.  At the moment you have too many what ifs floating about and you probably need this visit to realise how you have changed and possibly how he has too.   I will look forward to your post-visit post but whatever it says we can deal with it.   The metaphor ‘Rome wasn’t built in a Day’ has just sprung into my mind.   You are putting bits of your jigsaw together – it is probably the biggest puzzle you will ever do and it is never going to be finished in one visit.  
I hate feeling vulnerable too and it still happens at ***** but I do now know that I can rise above it – as you will.
Success is not the result of spontaneous combustion.  You must set yourself on fire first.