I second Luke’s recommendations for decent minimalist classical stuff. That Glass CD on the NAXOS label is only about 5 quid - so I agree, it’s a must buy. Maximum Minimalists is also a good one to get if you want a general flavour of this genre of music (or is it a ‘movement’?). I also recommend Morton Feldman (who’s compositions sometimes last for 5 hours or so) and Gavin Bryers (‘Jesus Blood Never Failed Me Yet’ involves an hour long loop of a tramp singing in the streets of London - sounds bonkers but it’s actually really moving).