A semi kit means that not everything is included to complete the model, the amount of material and fittings you get will depend upon the supplier though. Tyne Models specification seems to be quite comprehensive but there are likely to be some items shown on the plan which are not included in the kit and which you will have to make yourself.
Model Slipway kits, as you say, are very comprehensive and just about everything will be included.
You could always email Tyne models and ask them what items are not provided.
Colin
Edited By Colin Bishop, Website Editor on 02/06/2012 18:08:51