Thank you for your timely reply Toufiq. A staging site is not going to happen. Sorry. This is a personal website months away from going live, and I am not paying for webhosting for something you should already have set up for doing your own testing on - namely a latest Joomla install, with uncustomized, prepackaged Joomla template and your own plugin, as per my above noted environment.
Furthermore, thanks to the post on the forum from someone named Dominic, I have resolved my problem, temporarily, which has been to disable the SEF function on Joomla configuration, and change htacess.txt to .htaccess.
However, it is a temporary fix, because if you change it back to SEF on, then there is no access to the front end again.
If you could please find a permanent fix for this problem, it would be appreciated, not just by me, but perhaps by countless others, and I am hoping that your own testing environment should be sufficient to be able to resolve this glitch without asking for a staging site again. How can I keep SEF on configuration, with .htaccess and still have access to the front end editing? Looking forward to your solution. Thankyou.