BeciJ
What practice tests do you have? I assume you mean the NATS pdf they provide with the stage 1 test emails? You may find it beneficial to use the small number of practice examples they give to formulate your own questions just to get your confidence up a bit, if you feel you need to.
As they stand now I think the tests for stage 1 are:
Spatial reasoning (cubes)
Diagramming
Mental Arithmatic and
Motivation Paper
My stage 1 had each test bar the motivation test (a NATS document) done through a separate question booklet from SHL. Not sure if thats changed now (any current stage 1/2/3 candidates?).
Good Luck!