Contact your GP, they should get you an appointment soon.
If they can’t call 111. 111 may be able to get you an appointment for an ECG from a hospital or urgent care. Or some other intervention.
NHS inform is a much better place to get information than an internet form. It’s probably the best place for medical advice on the internet for non-medical professionals. It also tells you appropriate actions for your symptoms - treat at home, speak to pharmacist, call GP, call 111, call 999.