Tesco runs a partner programme as part of Tesco Direct home and electrical site which allows other businesses to take advantage of Tesco's huge customer base.
Tesco's Alexa ranking is 43 in the UK so you can see how important it is to UK shoppers. It has 9m unique visitors per month.
This allows Tesco to expand it's product range. This is by invitation you can email them but
them but not apply as such.
If you are interested then it is probably worth checking if your product range is adding something to their existing range rather than replicating a supplier or a range that they already have. Its for established businesses.
You would need to meet Tesco standards for customer service, refunds and their guarantee. In addition Tesco Clubcard points are part of the transaction so would be part of the cost of goods sold. Of course this is also a huge opportunity as Tesco is such a big business.
I am Mark Mandel. If you are looking to launch eCommerce project then get in touch. Mark_A_Mandel.