The aircraft would be handled by ourselves, and of course no need for fuel or anything else!
as mentioned previously, handling at Heathrow is mandatory (I think GA flights are handled by Signature, used to be Metro) & are most likely to be given a stand in the Cargo Cul-de-sac (near T4) or up by the fuel farm/T5
I think you need to apply for runway slots upto 3 (or maybe more) days in advance, not sure on this though?
FC