For winter cover you could try Green Manure - 'Landsberger Winter Mix'.

The place I ordered from is the first result on a Google search.

Simple low maintenance - turn them into the soil when ready for your main planting.

Hank. This is a (semi) joke reply. Andip is right but *why do you have spare space in your garden? *If you are a gardener you shouldn't have that. So sad. :o((

Thanks Andip, will check that out but what about Summer ?
And Sarraceniac - i'm not into flowers and we only like certain veg for which my raised beds are sufficient.

gosh we never have spare space in our garden... veg or flower

In that case, Hank, it sounds as if grass would suit the bill. You can put grass cuttings in the compost bin.

Thanks guys. But i was thinking about my daughter who threw a handfull of chard seeds in one of her raised beds and now has loads of chard up to 18 inches tall, which we wouldn't dream of eating, but would fill the area I need to fill and would help fill the compost bin on completion.
But as I've said before, I'm a rank amateur at this game.
And as for grass - we have a lawn, the cuttings of which don't go very far at all.

Just interested to know why you wouldn't dream of eating some of the chard?

Must admit we love it stir-fried with a little garlic. Great with things like lamb's liver or any grilled meat. Makes a slight change from spinach.

Chard is a great vegetable... growing veg just to compost seems all wrong to me somehow. Could you give them away to family and friends? In addition you can put too much green stuff in your compost.

Oh dear, I seem to have upset the apple cart here. As I said earlier, chard is tasteless ( to me anyway) maybe my son is cooking it wrong ? ( i'm not a cook either).
My daughter's kids ( who are vegetarians ) won't eat it either.
I guess I should pass Sarraceniac's recipe to them and give it a whirl myself.
But thanks for all the comments.

Please don't tell me you are boiling it! Steam gently and then finish off with a little butter and white wine. You can also add a little onion or shallot... Cooking is an art on I ;
love!

Out of curiosity what veg do you eat?