Weedkiller questions

Emma: my heart goes out to you what with the weeds and all! If you're not up to tackling them this year, try growing a few things in containers just to be GARDENING, start on the weed control next spring. Look into a pre-immergent that can be applied long before weeds begin germination, one that's aimed expressly at the nasty critters dormant seeds. I use a pelleted product that's applied with a hand spreader in very EARLY spring before anything begins growing, has done wonders for obnoxious weed control! By the time planting rolls around, it's safe to do it with no problems as the pre-immergent has done its thing by then. With any pre-immergent/weed killer (spray or otherwise), it isn't advisable to apply such products AFTER the problem has started as it'll continue to kill any seed planted if it comes in contact with them.
The very best time of year to begin perennial weed control (ones with taproots) is really in the fall: the plants are going into their dormant stage, are storing nutrients in their root systems, by absorption, for the following year, catch them then and they'll "ingest" the weed killer that'll do them in. Spring treatment of this type just "knocks" the weeds back for time being as nothing reaches the root system: they are pushing growth upward from stored resources, are NOT taking anything in as they do in the fall.
Hope this helps...

If the whole bed is nothing but weeds now & you've got no perennials or annuals in there currently, you could try the herbicide Round-Up. I don't know if it's available in the U.K., though. It will kill the root of almost any plant as it's non-selective - not so much woody stuff, though. I like it because it works well and the chemicals in it break down into naturally-occurring substances - including H2O - when it hits the soil (according to the manufacturer). It will not sterilize your soil either, but it kills every non-woody plant it contacts. Only a few hours on the leaves will do the trick. Basically the same approach as the plastic - kill it all. The only worry I'd have with plastic is heating up the soil too much & damaging apple tree root systems. Don't know if that's possible, but it was a method suggested to me years ago to get rid of verticilium & fusarium wilt, but I rejected it, due to not wanting to heat up the soil & harm my althea shrubs, or my Spring & Summer bulbs.

Round-Up is not organic, so if you're a "green" gardener, that probably is not a good option. Perhaps check online for organic herbicides? There is a company in San Antonio, Texas - Green Light, which has a lot of organic supplies available. And my sister-in-law uses organics from a company called "Medina".

Good luck and get well quickly!