Welcome to the forum, Croftboy.
You are not alone! Sorry this is worrying you so much. When you read the posts remember they're mostly from people with complaints. When everything's fine people mostly don't post. So don't think the worst!
You might cut out the wine and pizza for a month or so and see if that helps. Start keeping a food journal - look that up in the search box at the top of the page. You may find you have trigger foods like a lot of us do.
Omeprazole doesn't work for everyone, and as you said, you have been on a very low dose. If upping your dose doesn't work, tell your doctor and see if you can switch to another of the many products available.
I found that I could control my reflux events by eliminating my trigger foods. I still had a bad lower esophageal sphincter, LES, and had some stomach fluids leaking up when lying down, but at least what came up was non-acid. At least I didn't have the pain after eating and tachycardia (my reaction to trigger foods). Check your heart rate when you're having an event.
You really need to follow the manufacturers directions in taking PPIs. They don't work if you just take them when you have symptoms. If you take your dose first thing in the morning, followed by food after a half hour to an hour, then the medicine works better. The acid pumps have to be turned on for the medicine to work. Medicines that have to be metabolized need usually around 45 minutes to get changed by your body to the form that works.
I know it's tough to get anything done in the UK, but you might ask if you could have a barium swallow to see if you have a hiatal hernia and how bad your reflux is. It doesn't hurt and non-invasive. Scopes aren't really bad but they can miss things and won't show how the stomach is behaving when there's something in it. Getting the scope is something you must do though.