Thank you for reminding me about Heathrow Rewards, I'd forgot about them!
We just don't have time to schedule a trip to America, and I'm not sure how cost effective it would be. Our annual leave at work doesn't start until 1st April as we have used all our allowance until then (we are off to Antarctica for Christmas and new year - not flying from London though) and we already have two weeks in Iceland booked and 2 weeks in Japan!!
I'll definitely try and contact them before. Perhaps because I can be flexible when I go to them and the fact we are buying four rings they will help!! I'd literally be flying from Manchester to London return, just an hour flight.