KLM have a good network of regional airports in the UK and are worth looking at rather than going via Heathrow. Emirates also fly to a few major UK cities besides London.
If you enter LON into the search engine rather than Heathrow or Gatwick you can make some savings if you don't mind which of them you depart or arrive from as many airlines fly to both airports. With the extensive ground transport options available it may not make much difference, some people prefer Gatwick as it is smaller and has trains.