OK I'll try the tesco suggestion. Shame Lidl aren't doing it any more.
Anyway, I'm not sure I'll get anything close to bir / authentic curry from a supermarket. Maybe there's a deli somewhere (no, not the city, a shop!) that does bir / authentic curries that can be heated up. Or somewhere like whole foods that I haven't heard of. Or maybe there's an enthnic shop that sells pre-prepared meals that you just heat up??