This is probably the tip of a bloody great iceberg.
Have you ever met a poor bookie - neither have I.
You cannot help someone who does not want to be helped. Your H clearly does not think he has a gambling problem and you can only help your own self. You are woefully under qualified to help him and besides which he does not want your help. What you have tried to date (policing him) would never work and indeed has not worked. He is making you responsible for his addiction.
Do not let him drag you (and any children you have) down with him.
Ultimately you are not responsible for him. As mentioned you can and must protect your own well being.
I would contact Gamcare on 0808 8020 133 or GamAnon
It's like going off drugs and then back on. People are usually worse. Your dh is an addict. He could go to gamblers anonymous but meantime you cannot have any finances tied up with him. He will bankrupt you. Gamblers are notorious liars as well as as long as they have money to gamble they don't care what they do. It's a very crippling addiction. You could contact gamblers anonymous yourself for advice but please keep your money safe, even kids money boxes can be raided.
My DH is a compulsive gambler, though has been going to GA for a number of years and has been gamble-free for almost 3. It took a long time to get him there and the truth is there isn't really anything you can do to stop him gambling until he admits he has a problem and asks for help.
The only thing you can do at the moment is keep yourself safe financially so that he can't drag you down with him, and let him know you are prepared to help (if you are) when he is ready. Keeping a check on his account etc is a barrier towards stopping him gambling, so great if he'll give you access again but that alone will never be enough to stop it.
I really recommend GamAnon if there is a group near you, or I believe there is an online chat room from their website on certain days. They really helped me in the early days and I still attend when I can. They'll give you practical advice and will be supportive whether you want to stay with him or decide that this isn't something you can deal with.
I won't lie to you, a gambling addiction is horrific, and be prepared for things to get worse before they get better. There was a lot of debt that I didn't know about, including some in my name which only stopped once I took steps to protect myself (e.g. checking credit report, keeping cards with me at all times). However, there can be light at the end of the tunnel. We've come through the other side with a stronger relationship than ever. There's no guarantee he won't slip up and I will always have control of the finances, but he still regularly attends GA and never wants to go back to gambling.
The lies that they can tell are ridiculous and hurtful, but gambling addiction does take them over and they are not acting or thinking logically. I found it useful to separate my usual lovely DH from the gambling addiction - it wasn't him that was acting that way, it was the compulsion to gamble over everything else that was causing the behaviour.
I know exactly how you feel and I'm wishing you the best of luck
I found out my H was gambling every day in November 2016, He accessed Gamcare and got himself some counciling via the website and hasn't gambled since and been a much better person since. So it can be achieved!
But he needs to want to help you can't help him if he doesn't want to stop unfortunately.