Hi there
It has taken me 6/7 yrs to be taken seriously by doctors and cardiologists. I'm a great believer in you are the only person who knows when something doesn't feel right. It's your body and if you think something is wrong pursue it. I live on the Isle of Wight and eventually decided to pay a one off consultation fee to see a cardiologist privately on the mainland. Luckily my doctor was helpful and made some recommendations. If you are not happy with your doctor see a different one, it is your right. Or take the drastic approach and next time you experience this pain phone an ambulance or go straight to A&E where they will peform basic tests such as an ecg and bloods. If something is seriously wrong it will show up and this will get you in the system. Keep on at someone until they listen. Good Luck Emma
I understand that my recommendation has no "weight" with the UK government health system... but if sounds to me like you need at the very least a EKG and maybe a 24 hours heart monitor - and likely an echocardiogram would be a good test too as it will give precise measurements of your heart and valves.
I find you comment "interesting" as here in the USA as we are undergoing a major political battle over how much more government to inject into our medical system.