well Lindsay2301 it all takes time sounds and looks like you have been very busy but you got lots of time to do it all don,t try to everything at once you will sicken your self .
hello just read your post i don,t think a plumber will fit a unit for you but a joiner may be your best bet . plumber will do the pipe work etc unless he is a jack of all trades then you have landed lucky!
the heat should come through the front of the boxes but you my wish to try putting some tin foil down behind the radiator to force the heat forward hope this helps you.
i always put the first layer grass down then the next layer grass up keep doing this until your last layer should be grass down this will give you a nice loam soil in a couple of months time :wink: