Shops like Boots, airside at UK airports, charge massive price mark ups compared with high street prices. For bog standard items like shampoo, soap, suntan lotion, buy them in India. Alternatively, buy in the UK high street and put them in your hold luggage. You do not say why you want to buy them at the airport and take them in hand luggage. Expensive and heavy.
Best to buy duty free and take them through as hand luggage. I am sure the duty free shops will not arrange for it to reach the plane for you.