"Lol" wrote ...
Well actually it looks more like a bit of field that hasn't been
cultivated for years.
4 poles (100 m2), all covered in couch grass.
So far we have dismantled a couple of pallets and made a compost bin, but
probably can't compost couch grass enough to kill it.
Mares tail is also present in the area, so seeds are probably around
waiting for anyone to expose some bare soil.

Cover the lot in plastic and leave it for a year??? (Are we allowed to do
that??).

Potentially a lot of work here, important that any effort is most
efficiently targeted.

So please advise and suggest plans of action!

Many thanks

You will find you cannot dig out couch grass no matter how careful you are
and it will be a problem for ever. Spray with glyphosate (Roundup) while the
plants are still green and wait a few weeks and they will all turn brown and
the roots will be killed too. It's the only sure way to kill almost all
perennial weeds and start with a clean plot. Black plastic will work
eventually but by then you will have had notice to quit for not cultivating
your plot. Glysophate weedkiller becomes inert on contact with the soil so
it's not too bad.
Mares tail is another problem, you certainly cannot dig that out it goes
down too far and the foliage is naturally water resistant so it's difficult
to kill with weedkiller, we found constant hoeing off reduced it over time.
Spend the first 10 mins of every visit to the plot hoeing. It will be all
around and will come back from the surrounding areas but from our experience
it seems to move across an area in a wave of thick growth and just leaves a
few plants behind in it's wake.
One problem is, if the surrounding area is also infested with couch it will
grow back surprising quickly so it may be an idea to weedkiller the whole
area and reseed any grass paths with proper grass. Or use old paving slabs
like us to cut down on the work.
Don't put your compost bin onto soil infested with couch or it will infest
your compost making it useless.

--
Regards
Bob Hobden
just W. of London