My plan - please correct me?!

[huntsman]

I have run out of time as Spring is so hot it's almost summer, so I have dug a hole about 15" deep, by 20' x 15' for me first attempt at veg. (Oh, and herbs!)

I have maters, peppers, carrots, lettuce, eggplant and the herbs.

I have ordered organic compost (1 x tipper truck) which I plan to mix with the soil from the dug hole and add some horse manure, and thus refill the hole. I will water well, allow to dry a little and plant my seedlings, which have been growing indoors under lights for three weeks or so. That's it...

Please shoot me down and tell me what I can do better in the present set of circumstances.

Thanks!