Can anyone please advise best way / software to join .mts files from my camcorder

Unless you have software like Sony's Content Management Utility or NLE software like Sony Vegas, there are others, that does this correctly you will get video/audio jumps at the join points and sometimes sync issues.

There is free software out there that will join these files correctly but rather than trying to explain how to do this within the confines of a post check out:

My AVCHD Videos (http://avchdvideos.blogspot.com.au/)

This blog will explain quite clearly the software you will need, where to get it and how to run it.

Chris Young
CYV Productions
Sydney

You could also try 'multiAVCHD. Sounds easier! I always use the Sony software which works well but this multiAVCHD might be the answer.

Chris Young
CYV Productions
Sydney