What can't the voucher be spent on?

Some supermarkets place restrictions on what can be bought with vouchers. The below table gives full details.

Brand  
Aldi Aldi or third party gift cards
Lottery tickets, scratch cards or related material
Alcohol
Asda Third party concessions
Gift cards
Tobacco
Stamps
Petrol
Lottery tickets
Iceland N/A
M&S N/A
McColl's Exclusions:
Branded gift cards
PayPoint and PayZone products and services including bill payments and E top-ups
Mobile top-ups
Oyster
Postage stamps
Lottery tickets and games including scratch cards
Cigarettes, tobacco and e-cigarettes
HND accounts
Morrisons Gift cards
Lottery tickets
Sainsbury's An up to date list is available here. It includes:

Branded Gift Cards
All lottery related products
PayPoint products and services
Stage 1 Infant Formula milk
Tobacco and related products
Postage stamps
All in store concessions
Petrol and Diesel
Mobile phone top ups
Online delivery charges
Travel Money
Tesco Gift Cards
Waitrose Tobacco and tobacco products
Postage stamps
Scratch cards
Lottery tickets
Infant milk formula 0-6 months
Prescription products
Mobile top up
Gift cards
Pay cards
Car park charges