Bitsbox, my favourite UK supplier. The order was acknowledged immediately and the goods arrived next day by first class post. Bitsbox prices are very sensible (resistors 1p each in 50 offs for example) and they charge a fixed £1.75 delivery charge per order for UK first class post. I've now used this company several times and cannot fault the service. They stock a wide range of parts - certainly most of what I need for VLF-VHF experimental building - and the delivery is super fast.
G3XBM recommends Bitsbox.