Where are you located?
If you are in the UK, you can buy gift cards with Litecoin on the following site:
https://www.cryptodechange.com/Scroll right to the bottom to select the currency you want.
They sell supermarket gift cards, so in theory you can buy all your food using a card you paid for with litecoin.
If the OP is in the UK then it will be easier with the card can shop with your needs that will be purchased but it is only in the UK and in other countries can not do such a thing so consider first before buying something.
Average payment by Litecoin is very rare and I often encounter only bitcoin payments.