Well..... after being told my battery and my charging system was fine... I got my own multimeter and it appears the battery was fine at 12.7v but dipped to 7.5v when bike switched on. Bought a stator and regulator for £130 (Honda wanted £360 just for the stator!). Fitted both parts and it now runs at 14.7v when running. Been a fun experience diagnosing and fixing all this, learning about my bike Thanks for all your replies folks. Just glad it ended up being something simple.
Well done on sorting it. What nightmare though, you should go and have a word with the mechanic who told you the cgargingnsystem was "fine"
Can't believe there's another update here....... Started bike this morning to hear a loud, high pitched squealing sound.. I remember hearing this before all my issues. Without delay... I took stator cover off to find one of the bolts totally seered and flattened at the top (if you seen my other thread... I had thought previous owner has soldered the bolts!). All the bolts were loose holding the stator.... one of them seered... fortunately I had a replacement one and tightened them all up niiiiiiice and tiiiiiight! I will check them them regularly so see what's happening. But this is strange.
