I'm still quite away off mate cos I have been finishing off some other moulds including the Clio bonnet (see seperate thread) plus I will want to get it on the dyno and mapped before I release any. You would be quicker getting one from AC. If you go with the fiberglass one the inside will be smooth enough, not smooth like plastic but nothing to get worried over.
You'll find the only difference betwen the carbon ones and the fiberglass ones are obvously the weight but the carbon one will provide a better insulation to heat transfer than the fiberglass one but not so much that you would actually notice unless you were a serious racer that is.
The bracket to move the expansion tank is only £10 from R-Sport, its the extra pipe work from the radiator to the expansion tank that costs nearly £200