Sore achey leg after 3 long haul flights, dvt ruled out by doctor, however leg still sore 2 days later. should i go and get bloods taken?

DVT risk from: flying is real but is sometimes exaggerated. And, a 3 hour flight would be relatively short in terms of increasing risk. If you're generally healthy, it would be very improbable for you to have a DVT, especially if your physician doesn't think you have one. It's more likely some musculoskeletal strain. As Dr. W said, if you're concerned it's best to speak with the doctor who examined you.