\\\\The pain management clinic have recommended that I take a low dose for severe arthritic/rheumatoid pain .\\\
The key phrase is "low dose."
Observing many of your threads over the years, i assume that you are not getting adequate pain relief from conventional painkillers.
If that IS the case, then i would certainly give amitryptiline a trial and no, i would not have an ECG or blood tests before.
Yes...I would throw caution to the wind and no, i have not had experience in taking the drug.