I am considering a 42 mile commute to London through A21->M25->A2. I don't know much about motorbikes, but back in the day I used to ride a Royal Enfield classic 350. My main consideration is mileage but at the same time I do not want something under powered on a motorway. I never rode a sports bike, so I don't know how it feels like to ride long distances. Any advise is highly appreciated. I do not want to spend a lot of money as well. I am considering something around £2000-£3000 mark.