Throw it straight on the raised beds and dig it in. It will be well rotted and warming the soil by the end of April so you can plant your own plugs out. Thats what I do with mine and it seems to work well.
Good Luck

James

__________________
My new personal website and photo gallery that now includes my garden, radio and my now world famous Food Diary of an Average English Man Blog

http://www.m6jdb.co.uk