Well I had a much better experience with streaming last night.
I checked the Wi-Fi signal at my Wi-Fi Sony Blu Ray Player with my Samsung Galaxy Tablet - it was 'Very Strong' - so that is not a problem.
I selected Disney's 'Beauty & the Beast' - normally not my type of movie but it has brilliant colours, razor sharp rendering, beautiful sets & top notch CGI. The 1080 feed was excellent as was the surround sound track.
The movie played entirely with no hiccups of any kind. So, I can only assume that sharing 6 devices with the router while trying to stream is not a great idea. Time will tell I guess.
So I'm mildly optimistic that this might be a viable solution...