Can I buy foreign currency at Manchester Airport Departure?

Flying away to India, need to know whether I can buy Indian Currency at Manchester Airport Departure Lounge? Also, do they deal in Indian Currency, because checked at highstreet exchanges and they do not deal in Indian Currency.

Just need change for £500, is that legal and do I have to pay them in cash or pay by my bank card?

What is a VPN?

VPN is (Virtual Private Network) were first used by companies to enable their employees to securely access internal systems such as email remotely (e.g. from home or while on business trips). Today they are increasingly being used for personal use by individuals to protect their privacy while online in public places (e.g. when using the wi-fi connection in a cafe) or in a country where the internet is censored / blocked (e.g. China, Saudi Arabia…).