Hello and welcome to HealingWell. I checked for info re antacids in UK and found this info for you.
Antacids are a type of medicine that can provide immediate relief for mild to moderate symptoms of indigestion. They work by neutralising the acid in your stomach (making it less acidic), so that it no longer irritates the lining (mucosa) of your digestive system.
Antacids are available in tablet and liquid form. You can buy them over-the-counter (OTC) from most pharmacies without a prescription. Check with your pharmacist if you are unsure about which type of antacid is suitable for you.
The effect of an antacid only lasts for a few hours at a time, so you may need to take more than one dose. Always follow the instructions on the packet to ensure that you do not take too much.
It is best to take antacids when you are expecting symptoms of indigestion or when they start to occur. For example:
This is because antacids stay in your stomach for longer at these times and have more time to work. For example, if you take an antacid at the same time as eating a meal, it can work for up to three hours. In comparison, if you take an antacid on an empty stomach it may only work for 20 to 60 minutes.
Do check with your pharmnacist and ask about a liquid antacid similar to what Joy referred to, Maalox here in the USA.