SVA
Single vehicle approval. Used for kit cars and one offs and by manufacturers who make less than 50 of a given car in a three year period. It is effectively a super MOT.
LVTA
Low volume type approval. Used by low volume manufacturers who exceed 50 of a given volume in three years. Most still use SVA by applying for more than one "ministers certificate" for the same model simply by changing the model designation.
TA
Type approval. Used by main stream manufacturers.
From 1998 all cars must have passed one of these to be registered in the UK.