Tesco's store at The Meadows, closed by fire last Thursday, will be back in business in eight weeks - by early October.
The petrol station reopened for business on Monday.
Meanwhile all 900 staff are keeping their jobs, many redeployed to other local Tesco stores while others are still helping with the clean-up.
The blaze, which was spotted by a security guard at 2 am, swept through the roof and destroyed the warehouse building at the rear of the store, packed with food, clothing and drinks.
There were between 40 and 50 staff and 12 shoppers in Tesco at the time and they were quickly ushered to safety.
The main store suffered only smoke and water damage, however, and hundreds of Tesco staff volunteered to work through the early morning clearing the shelves.
All the perishable food had to be condemned, while the tinned and packaged items were sent off to be checked for damage.
Steve Gracey, a Tesco spokesman, said: "The main thing is that nobody was injured, the evacuation went smoothly and the design was vindicated in that the fire was contained to the warehouse.
"We are really grateful to the three fire brigades which attended - Hampshire, Surrey and Berkshire - who co-ordinated the fire fighting superbly.
"I have never seen anything like it and hope I never do again." The fire was out by 5 am, having been fought by 75 firemen.
Mr. Gracey paid tribute to the spirit and enthusiasm of Tesco staff who turned up un-asked to lend a hand, many coming in even though they were on holiday.
"They are doing more than their bit, morale is high and our staff have been phenomenal. Many customers have also phoned the store manager to pass on their best wishes."
The cause of the blaze is still being investigated and the cost of the fire is not known and will not be released.
Ironically Tesco's at Sandhurst had recently been extended and revamped to include many more non-food items, like electrical goods. "We will be back better than ever," promised the spokesman.
Meanwhile Marks and Spencer, next door, is trading as usual as its building was unaffected by the fire.