First, don't be worried, be positive and take action, which you have.
When one feels a heard heart beat it has to be the ventricle and may be a Premature Ventricle Contraction (PVC). These are common (I'm not say most people have them) and happen even to the young (people under 60 is what I mean by younger). Your cardiologist may put you on a heart monitor so that the feeling you have can be recorded. These recorders usually start with wearing one for a 24 hour period, and then go to longer periods if an episode isn't recorded during the first 24 hours.
The beta blockers may give you some relief and will likely slow down your heart rate. This sometimes causes brief periods of dizziness, especially when one changes their physical activity level suddenly, such as "jumping" up form a seated position to answer the door or telephone. This can happen to people without any heart problems or medications. I have trouble with Metoprolol (a BB) if I take more than 100 mg a day. That is a very heavy dose. I'd guess you are on something closer to 25 mg. Just guessing, but trying to say if you don't get dizzy, that is fine, in fact that is great.
Thank you for your comment. That IS a heavy dose! Im not surprised theyd make you feel dizzy. Im on 40MG propranolol. Iv been on it 3 days now and can already feel the diffrerence in my heart...in a good way. i dont have any problems on it tho i do feel a little tireder than usual but i guess thats just one of the effects which i can live with. Id just like to ask..if i do have to have the monitor then wont the medication hide anything thats going on with my heart or will i have to stop taking it a few days/weeks before hand for the readings to be accurate if it is PVC will have need to take meds all the time or is there anything else that can be done? I dont want this to carry on as it sometimes gets too much, it doesnt make any differece to what activity im doing as i can wake first thing in the morning with the awful feelings. I am an active person, not overweight and eat quite healthily.