Cheapest way to get to Katmandu

Hiya

Yes I KNOW I could do my research, but its much easier just to ask here....if you are flying from London, England--is it cheaper to fly from London to KTM or is it cheaper to fly to Bangkok or Delhi--or some other larger city, then take a more local airline?

Also, can anybody recommend a guide for some lazy people who really just want to do an overnight trek?

Thanks

T