AstraVanMan wrote:

But anyway, it looks like the cheap tickets (£16.60 for 2 adults, 1 kid,
with family railcard - all zones travelcard return from Gatwick) should do
the job fine for the journey from Heathrow to Gatwick via Barons Court,
Victoria, and changing at East Croydon.

I believe there's a Southern-only version for even less. That might
make sense for you, as it sounds like you want to use Southern.

1. Will the lack of the tickets having been through any ticket machine
before getting on the tube replacement bus at T4 (or tube at Hatton Cross)
cause any problems (as effectively they're using it as a single ticket)?
(Sorry if someone did answer this before!)

Doubt it. (I'm assuming these are being bought in advance, as the Tube
ticket office at Heathrow wouldn't be able to issue such a thing, as
you're not strictly meant to do it in that order).

2. Will changing from a Southern tran to a FCC train at East Croydon involve
much in the way of stairs?

It might be same-platform, but if it isn't I recall that there are
(long) ramps but no stairs.

http://en.wikipedia.org/wiki/Image:E...g_-_270404.jpg
might show what I mean.

Neil