welcome to the forums.
For the warband you can easily make this by buying a box of emipire milita and if needs be an empire general spruce, this allows your captain a more armoured look and more weapons (Bigger and grander) to use, just stick to the fun of ranged weapons on your marksmen and captain / champions if you can afford it and your set.
For terrain its extremely simple to throw together 10 building sfor very cheap, Your probably talking about £20 total to build and paint them all and still have change left over.
For the materials alone i was able to build 10 well sized buildings (Some bigger, some smaller but all decently sized) for £10, thats the balasa wood, foamboard and glue. the extra 10 would prob buy you the modeling knife (Remember to stay safe... wow i sound like a disclamer add) and paint , some pva glue to seal the edges.