Not sure where you are in the country, but putting blueberries in the ground has been a success for me in Essex, even though I've had to obtain ericaceous compost to start them off.
Think I've had my bushes growing 4 or 5 years now, and get good crops. You've got acid soil so that's not a problem. But, blueberries don't like to dry out, and there's a real danger that could happen when they're grown in a pot.
Don't know about the quality or size of the Tesco plants, but hopefully you should get fruit in 2 -3 years.