I am spending 3 nights in London from 31st March as a start to our European adventure. We have a group of 3 adults, 2 children (10 and 12) and a baby (8 months old). I have already booked accommodation at the UStay in Greenwich and tickets on the Big Bus. What I am wanting to know is the best way to get from Heathrow to our accommodation - it will be at around 5:30pm on a Sunday. We are going to Paris after London and I have bought Eurail tickets for that. I assume the train is the best option for this transfer. Thank you so much for any help you can provide!