His early childhood was in Moscow where his father served in the British Embassy for 18 months. When his father moved back to the UK to work for the BBC, Tim went to Datchworth primary school. Later his father ran The Near East Broadcasting Station Sharq al-Adna; his mother taught her children by PNEU until Tim went to The Junior School in Nicosia as a boarder. After the Suez débâcle, his father returned to the UK to train as a parson, and the family lived in Oxfordshire, Wiltshire and Dorset. Tim boarded at the Perse school to age 15 and then to Dauntsey's. From 1964–1967 he was an undergraduate at the University of Hull, obtaining a 1st Class Honours BSc in Mathematics. In 1967-1969 he began graduate work at Hull, taking a sabbatical year as Student Union President. He then moved to the University of Warwick to take a PhD in Mathematics.

Less well known is his role as active founding member of COUM Transmissions performance group with Genesis P-Orridge. They studied at Hull University together. Tim Poston wrote texts and advised COUM on physics and mathematics 1968-1978. Tim Poston remained "Scientific Adviser" to P-Orridge up until his death in 2017.

His PhD thesis on "Fuzzy Geometry" was supervised by Christopher Zeeman and the PhD was awarded in 1972. This topic, otherwise known as “tolerance spaces”, is similar to topology and should not be confused with fuzzy logic.

From a very early age Tim discovered he not only liked to read science fiction, but loved writing down his own stories too. This ultimately lead to the co-authoring of an SF novel The Living Labyrinth, published in 2016 by ReAnimus Press, and its sequel Rock Star in 2017.