Quick thoughts, in case they get you going in the right direction...
1: sea purslane, Halimione portulacoides, perhaps
2: Rumex perhaps
3: Galeopsis, probably G. tetrahit
4: can't think...
5. Berberis vulgaris
1 are you sure it's sea puslane, the leaves aren't succulent (& it didn't taste salty!) This was growing in Berkshire
2 I wondered if it was a Dock but can't tie it down - are the leaves right for a Rumex?
3 & 5 Thanks - that's them!
4 any takers? Again, growing in Berkshire
I agree with Mike on pic 2 being a Rumex, leaf and seed characters will take it to species. I'm sure it is not a Reseda as they have obvious petals. The leaves are simple enough and flowers are right for Rumex sp.
No.4 I am sure is a Veronica species - toothed margin to leaf; opposite leaves and 4 fused petals. The most likely species from the characters I can see here is V. officinalis. It is not in the Borage family as they have simple, alternate leaves with entire margins and 5 petals.
No.1 might be common purslane - Portulaca oleracea or Amaranthus blitoides - which are both recorded for Berkshire here so might be worth sending your pic to have it verified by the local BSBI vice county recorder Mick Crawley email@example.com Try to include the location and grid ref if you do...