Hi Dylan and welcome to the forum.
I am sure you will be reading the other stories here so you will know that you are not alone with this problem. You will aslo have read some of the things that have helped others to stop, which things can you apply to your own situation?
The first thing I would recommend would be to contact your usual gambling sites and ask them to exclude you. Then when you want to stop you can’t change your mind or get tempted by those offers. Once excluded those offers should stop anyway from that particular site. Investing in a gambling blocker, such as Gamblock, will stop you visiting any gambling sites on your PC.
Now you don’t want to lose that £1000? So, who can look after it for you? Make yourself accountable so that you can’t use your money for gambling.
Keep posting here, use the other support that you have available, such as Gamblers Anonymous, Gamcare and more.
Get some of those barriers in place and keep posting here to tell us the positive steps you are taking.