There are three possible pronunciations. Most people probably pronounce the name ‘Bark’, the same as J S Bach the famous composer.
However, the Bach family originally pronounced their name ‘Baytch’ (to rhyme with the letter ‘h’). When he was a medical student his fellow-students mispronounced his name as ‘Batch’, and the mistake stuck. He was known as ‘Batch’ throughout his medical career, and we still say ‘Batch’ at the Centre to this day.