I have stayed 4x at Premier Inn Waterloo. Hotel has A/C, bar, restaurant, entrance is street level, walking distance to Westminster Abbey, London Eye, Parliament, Thames River, Big Ben, Hop On Hop Off, 2 tube stations, Waterloo train station, regular bus, stores, restaurants, pubs, small grocery store.
www.premierinn.com
I used Just Airports, a car service from Premier Inn Waterloo to Heathrow.
www.justairports.com