[NellyCB]

I'm thinking of sowing some red clover as a green manure on the ground I'm not using for a while. 

I've nevert tried it before - is it a case of just digging it in later on (a while before reusing the ground)?

Also what is everyone else sowing manure-wise (if anything else)?

[Ricey]

Im new to lotty's and I found this site informative. It explains the various green manures well.

http://www.sowseeds.co.uk/green-manure-seeds.html

With deep rooting green manure, you will need to dig it in very well, 3 to 4 weeks before you plan to plant your main crop. These plants send their roots very deep and will return unless dug in well.
I believe the best procedure is to first cut down the plants to ground level the dig over the area. Chop up the roots well and leave the clippings in the ground as organic matter.
(I dont think you should allow the plants to flower, although you'll need to check on that)

Green manure seems to be a fantastic idea, because weeds will be supressed and the plants will condition you soil as they grow as well as eventually acting as manure.

I used my own mix to cover 2/3rds of my newly aquired lotty, hoping to be ready for next spring. I used, Clover, Field Beans, Rye Grass ands Alfalfa. In the 4 weeks since sowing, the newly dug over area has a nice low covering of green manure
Some green manures compliment each other as they grow (Like companion planting), Just do a little research but dont take too long..... You'll need to get sowing pretty soon.

[NellyCB]

Thanks Ricey.
So I don't let the plants flower? OK.
I may try some of the others you have tried, especially Alfalfa.

[Salmo]

Rather than pure clover you should consider one of the standard Winter mixes with italian ryegrass.  One mix I used also included a little mustard which established very quickly and acted as a shelter crop. Once I could see that clover and ryegrass was established I cut off the mustard and composted it.