Wiggy, I think you will find the local buses in and around LHR are free.
My earlier remark concerning the Hotel Hoppa services
to get to local hotels lead to Wiggy's helpful reminder that TfL busses are free in and out of LHR to stops on the airport perimeter; indeed, I've used them many times for the Bath Road hotels if meeting up with mates for sharpeners after a trip. But not all hotels that purport to serve LHR are on the perimeter (or even that close for that matter); the 'Windsor Marriott' for example is actually in Langley and accessed via Colnbrook; there are two Hilton's - one is a 10 min walk from T4 and the other requires a cab or Hoppa which makes numerous stops en-route and is quite different to hotel shuttles I've experienced elsewhere.
The Pheasant in Harlington would be my preferred choice for refuelling; easily walkable from Bath Road TfL Bus Stops and a decent Tandoori just 5 mins away....only downside is they're both landside
