Posted: 27/06/2017 at 07:59
I obviously can't see how bad the border is but the gardener probably suggested machinery as most people won't be willing or able to pay for the amount of time it takes to clear weeds and brambles properly by manual labour. Its also very time consuming to work around existing planting if a border is very infested with weeds. If brambles have taken over then it may be more cost effective to use machinery to clear them and the border completely so you have a blank canvas or accept it will take several applications of glyphosate over several months.
We are restoring a neglected garden and out of interest I have been logging the time we spend in the garden on various jobs. We have been steadily clearing a border similar in size to yours where alkanet, couch grass and brambles had taken over. Our log shows we have spent over 100 hours clearing it and digging it over. we are not in the flush of youth but reasonably fit and able so get a resizable amount done in each session - weve had to clear each section several times and dig down a couple of feet to clear roots and like yours have also had to work around tree roots. we were shocked when I totted up the hours. We are now on what I call maintenance weeding but still a higher level that I would hope for in a cared-for garden, partly because we can't afford dense planting so have lots of bare soil and we have been clearing organically i.e. by hand so still fighting stubborn pockets od perennials and years worth of alkanet seeds in the soil.
I'm not saying all this to depress you, but do be realistic about how much time (or money if labour is bought in) it will take to clear/restore a border where weeds have started to get the upper hand espevially if you aren't happy with a more relaxed/shaggy look (maybe the country look you describe it as been currently).
As other members have suggested there are lots of plants that will survive in shade and many that will act as reasonable weed suppressants. Some of the tough do-ers used in municipal planting may also be a good choice such as cotoneaster, hypericum, ivy (as ground cover).