scorpy66 wrote:
[...]
Any tips for the following would be hugely appreciated:

1. successfuly removing the twitch
2. what chemicals to use (we have cats)
3. whether more than one treatment would be necessary
4. advisability of weed control fabric to help prevent recurrence
5. care of existing plants while digging up, potting and replanting
6. anything else I've overlooked!

What they said. On (4) above, forget it. Couch spreads sideways, and
will just pop out at the edges and all the holes you make for your
plants. The stuff has its uses, but it doesn't replace gardening
operations -- in fact it can hinder them. Use Roundup, and when you're
sure it's all gone, use a conventional mulch as Janet suggests. You'll
still have to walk round every weekend to nip out any weeds that
appear, but it shouldn't be too much trouble if you've prepared
properly: you should be able to do it while Him Indoors does the
hoovering.

--
Mike.