The Food hall and the tea section is one of my favorite parts and it is incredible. I also never miss the French Tea Room on the ground level. The pastries and teas are fabulous and they dont break the bank.
Guys and Ladies if you dont want to max out your charge cards avoid the fragrance and accessories section. They have everything and the prices are competetive BUT its too easy to go wild. Mrs Professor strolled out with 500GBP in Perfumes and nearly 3000 GBP in new purses, wallets and such. I had to drag myself away from the custom watches which range up to 200,000 GBP or we would have needed a THIRD mortgage on the house.
Its a no miss experience but you may want to lock up the all but one charge card in your hotel safe to stay out of trouble.