Would anyone care to hazard a guess at roughly how long it might take from
official landing time to exit Heathrow terminal 3 and walk as far as the
central bus station or tube, when arriving from a non-EU origin (but with UK
passport) in the late evening (with luggage)?

I know there are loads of variables and I imagine the answer will be 'a
while' but just wondering about how tight onward connections might be at that
late hour.

Thanks
Theo