Louise, you should not have to live with those symptoms so I think it's time to take matters into your own hands. You can either go to your GP and insist on HRT and if they refuse, get a private prescription - please read Professor Studd's website, he is an expert on the menopause and he does telephone consultations in that helps.
I realise you have a heart condition but you have to think about quality of life and it is unacceptable to expect anyone to live with the symptoms you have.
In your position, I would take HRT without a shadow of doubt.
I hope that helps.