I now have for sale some replacement T5 & T10 bulb holders. You generally find them used in the dash clocks for the illumination bulbs (may find them elsewhere to).
T5 are 50p each
T10 are 75p each
P&P is 66p for 1st Class or £1.40 for Recorded Delivery within the UK per order.
Picture is of the T10, the T5 is the same but smaller.