A neighbour has asked me to tidy up her garden, which hasn't been looked
at for about a year.

There are lots of weeds (e.g. couch grass) growing up between the
flagstones in the paved areas.

I was going to use Glyphosate, but when I checked on what tools are
available there, I found a weed blowtorch: how effective are these
things, please?

Cheers
John

p.s. Yes, it's the wrong time of year to be dealing with weeds, but
needs must!