Discount fuel?

If I go to the supermarkets here in Australia, spend more than A$30 (15 quid) on my groceries, I get a 4c a litre discount voucher on the bottom of my receipt.

On going to a discount service station (Caltex or Shell), I can fill up, present the voucher and get the discount off the price of the fuel (petrol, diesel or autogas).

Also, being an AA member, I can purchase Woolworth supermarket shopping cards for 5% less.

For a $100 Woolies shopping card, I only pay $95.

This lets me buy the full $100 worth of groceries, but also $100 worth of fuel at Caltex (who have a discount honour deal with Woolworth's)

So . . . if a litre of petrol is $1.39, I can present the 4c discount voucher at the bottom of my shopping receipt, taking the price to $1.35. Then if I pay with my Woolies shopping card I get a further 5% off, making my total outlay only $1.275 for a litre . . . a 11.5c saving.

What discounts, if any, are available on fuel for you lot in Blighty?