Astro turf DIY

[Catontoof]

I have grass in my back garden but it's also mostly mud, so not great. Lots of weeds.
after years of trying to get grass nice I have decided to try snd lay astroturf.
would I be able to
lay weed killer membrane on this then a Astro turf underlay? Or do I need to do something else

Please don't do this.
It's such a dirty trick to play on nature and wildlife
Does it really matter if your lawn has weeds in it? Can you do something to improve the drainage if it's always muddy?

You need a proper sub base for decent artificial lawn. MOT Type 1 that is then compacted, then weed membrane, then sand and finally your artificial grass.