what in the heck is this

Sorry im getting advice from family as well . I have read ALL the comments but i dont understand the reasoning behind a lot of the comments and i think a lot are coming from people who are not appreciating the variety of life circumstances people are in the UK . Yesterday i used
wilko Rootkill Extra Tough Weed Killer Concentrate - Green diluted to around 4 Litres
today i got a non glycophosphate and glycophosphate one. I havent decided which one to use yet
In relation to the contaminating ground water and not doing gardening comment . When we bought the house there was no garden. The previous owners had a huge high quality studio and the rest of it was paved. I guess there was a buddleia plant but i dont think they had deliberately planted it. Eventually we got rid of the studio as it wasnt used and was an extension to the house we never used. 50% of it was taken by builders and the rest was crushed. The garden is besically rubble from the studio covered by weedproof membrane and gravel which is why i dont understand why people are talking about ground water contamination , digging ( what exactly am i meant to use to dig down compacted rubble and soil breaking down the weedkiller as there is no soil.
On looking its obvious the neighbours have allowed their garden to be generally overgrown. I cant find a record online of when their home was bought

 

thats reassuring im leaning towards waiting a little while before applying more weedkiller as quite a lot was applied . Maybe it is my bamboo anythings possible

 

Very little chance of it being yours.
Below the gravel and the rubble is soil and groundwater.
Don't bother with the non glyphosate weedkiller, it would be like trying to stop a tank with a pea shooter.

 

If rainwater can drain through your membrane and rubble, then so can water containing weedkiller, and that is how it can end up in groundwater. That's where water goes when it trickles downwards into the ground, whatever is covering that ground, vegetation or asphalt or concrete or gravel or wood chips, etc. It is then part of the water cycle.

 

Your picture just shows a few nice looking mature shrubs. If it was left to be "generally overgrown" I'd expect to see brambles etc coming over the top of the fence and lots more weeds encroaching at ground level.

 

i read that triclopyr was good for woody plants and then shoot stems are definitely covered with a thick wood on the stem

 

There is another method but whether it's applicable in your circumstances I don't really know. I have a huge Ash tree in my garden ( a Conservation Area so limits apply ) which means I get numerous Ash tree seedlings and saplings everywhere. Catch the seedlings early enough and they are easily pulled out. However, having also got a number of other trees and thick shrubbery, they are easy to miss until they become obvious. Too many other plants around to really be able to dig out so the easiest solution I have found is to shave the outside of the stems to ground level and the sapling will eventually die and can then more easily be removed. As an addition, once shaved, you can carefully paint the now bare stem with a suitable weedkiller, bag or bottle it and leave it.
BTW, I think you are perhaps being somewhat presumptious when you refer to people here not being aware of dealing with the various circumstances life throws at us. This is, after all, a gardening forum and if after 5 pages you are not happy with the advice/info/ideas you have received so far, then that is a pity. Only remains to wish you Good Luck with finding the best solution to your problems.

 

It's hard to tell from the picture but isn't the plant on the left a bamboo? It certainly has bamboo like colouration and I think I can see a new culm growing up.
If that is a bamboo then it looks like it's been managed as it's only in one area and quite thin (from the picture), so could be being managed.

 

Unfortunately trichlopyr is a selective systematic weedkiller that acts on dicotyledons it doesn't work on monocotyledons (grasses) so you can use it to kill dandelions and such like in your lawn.
The bad news is that bamboo is basically a grass relative so trichlopyr does not affect it..