No fixed roser patterns as such although you will be able to "bid" for work once you have a few months seniority under your belt. Until then you will probably be awarded "blind lines" which is dealer's choice of a month's worth of work although you can request days off. I live approx 45 mins west of Heathrow and it's never been a problem. You're a bit further west but I can't really see it being an issue. Once in, you could bid for tours which would give you the minimum number of reports at Heathrow. Hope this helps