when is the best time to spread muck,plus more

muck spreading may commence now   

Weeds - if perennial, they may just push up through the muck.  I might be inclined to dig up, hoe before spreading but that's my opinion

Strawberry plants - I think about now/October and bare rooted canes in late October/early November.  Plants in pots tend to be all year round (ish) but more expensive than bare rooted ones.

I agree that once you've cleared your garden, or want to start a new one, now is the best time.

But before I do mine, I always fork out all the weeds. It's the taprooted ones that'll give you grief in spring and split or chip into new ones if/when you rotovate the manure in. My mum has more problem with perennial seeders and has just finished pulling out barrows full of them prior to manuring.