Shopping on a plate: your online Christmas dinner

The countdown to Christmas is on and although many recession-afflicted Brits will be looking to economise, the supermarket checkouts will still be busy and that means queues and car parks full to bursting. So why not take the strain out of your yuletide food shopping and go online?

Many of the leading supermarkets – including Tesco, Sainsbury's, Asda and Waitrose – offer an online grocery service, although Marks & Spencer doesn't deliver food apart from in hampers. With petrol prices still high and time precious, many consumers find home shopping both convenient and economic.

For a small charge, the supermarkets will deliver at an appointed time to your home. However, not all UK addresses are covered. As a rule, the UK's towns and cities enjoy very good coverage, and the rural areas less so. Generally, Tesco has the widest distribution network across the UK as it has multiple depots, while smaller players such as Waitrose deliver to fewer areas.

The good news, though, is that most of the supermarkets operate seven days a week and at all hours, although some have a less frequent service on Sundays.

Charges can range from 99p to £9, although you should expect to pay between £3 and £7 for most deliveries. That said, Sainsbury's will deliver for free midweek provided your order is for more than £100.

The supermarkets vary their charges according to what time you want the item delivered. Commit to waiting in for the van on a weekday and you'll pay less than if you ask for your groceries to be brought to your house after work or at weekends.

Although most online services offer home deliveries close to Christmas, all the supermarkets say it is best to book early as slots will fill up fast.

If an item on your shopping list is unavailable, a "logical" substitute will be provided, which you are free to reject on delivery for a refund. Where an item is replaced by one of higher value, Asda and Waitrose charge customers at the lower price.

The main drawback, though, is that you can't physically pick the goods you want; you're relying on the staff member in the supermarket's distribution centre to give you the freshest produce, rather than something close to its sell-by date. So to an extent, shoppers are taking pot luck.

Last year, consumer group Which? conducted an undercover "mystery shopping" exercise and found that food bought online is 1.28 days nearer its "best before" date than produce available in-store.

Laura Starkey, from the consumer advice website Fool.co.uk, points out that there are a number of ways to ensure you receive fresh food. "When you shop online, you give up control," she explains. "But some websites, such as Ocado, will give you a product idea and provide you with the sell-by date before it gets to you.

"If you want a Christmas delivery, you would need to book it early, but you could also stagger the process by getting booze earlier and then the veg a little later."

And there are savings to be made on delivery costs or the groceries themselves, as supermarkets compete for yuletide business. "Often you can find online voucher codes on forums such as Hotukdeals.com and websites such as MyVoucherCodes.co.uk, where you input the code at the checkout and it offsets the cost of delivery –and most of the time it will be free. We will see more of this the closer we get to Christmas," adds Ms Starkey.

However, consumer groups believe that the best deals are to be found offline rather than online because supermarkets will sometimes keep their cheapest products and one-off special offers in-store. In addition, while the budget supermarkets, such as Aldi, Lidl and Netto, don't offer home delivery, they have still been stealing a march on the traditional big names.

"We are now seeing people flocking to discount retailers," says Sarah Dennis, a researcher at Which? "Aldi and Lidl beat the big four supermarkets in our recent survey. We looked at the quality, and in a lot of the cases Aldi and Lidl were just as good as Tesco. Price is the main reason for shopping at these stores."