<<if an aircraft familiar with LHR (e.g. BM or BA) makes no statement or emergency call about his fuel state, what would an ATCO, from his training, "expect" the aircraft to be able to do in terms of go-around, diverting, further radar circuit(s) etc. from just before touchdown ?>>
Hi Nigel. ATC would expect the aircraft to make a standard missed approach and then be radar-vectored for a further approach. If the pilot wished to divert it would be impractical to issue a SID so, again, radar vectors would be employed to get it into the departure route.
In bad weather when crews are aware of their fuel problems they will usually warn ATC in advance that in the event of a go-around they would like to divert to xxx. ATC then usually issues them with the appropriate SID to use following the go-around.
Does that answer your questions?