I was supposed to take it out this morning, to defrost today while I was on a course. Now its almost 4, and I've only just taken it out. should I decorate and leave to dry off or should I let it defrost for a few hours then decorate? Its for tomorrow so I dont want to have it still soggy when they pick it up and I dont know what time that will be!

let it d, then decorate as usual, good luckefrost a few hours, this is all it should take

Is it just cake? cake and filling? crumb coat? final coat?

Definitely let it defrost before decorating.
And knowing if it is crumbed, iced or what would help w/a better answer.