Reflex syncope (also known as vasovagal syncope), and POTS.
Arrhythmia monitoring is imperfect because arrhythmias often don't occur when the monitor is being worn. Various alternatives are becoming available. Search for Kardia Mobile, Prince 180B Easy Handheld Monitor, Zio Patch. Some of the monitors are substantially cheaper second hand.
This has changed recently as NOAC drugs have become available. See the BHF page on NOACs for more information. European Society of Cardiology patient information cards can be downloaded from here (below the link to the full guide document).
The European Society of Cardiology has a large website. There is a section for patients. Clinical guidelines are also available but please be aware that these are lengthy and primarily intended for practising cardiologists.
With so much information on the internet, knowing where to start is the main issue. These are my top recommendations. Other websites are listed lower down the page.