Atilla, try this email address during normal office hours;
The Tyne plan you have found is drawn at 3/4inch to 1foot (1/16th scale) and was designed to be used with a ready made hull( ?? still available) from Model Boats. The drawings from the RNLI are at 1/20th scale on three very large sheets. If you wish to build at 1/12th scale ( “normal size” for modelling lifeboats ) you will have to do the calculations needed. Either way in my opinion the best route is to have all the plans/drawings/pictures you can get your hands on to build an accurate model. Remember that all the boats in the class were slightly different because of repairs/refits during their lifetime so choose a boat and timeframe to model to produce the best job you can.
My 1/12th scale model of the RNLB Phil Mead, Teesmouth Lifeboat Station just before closure a couple of years ago.
Mike