Hi,
I have the above with a standard ariel and all is ok accept I can't go to the Freesat service until I get my "special" ariel.
Does anyone know - if I get a freesat dish does the new cable replace my old cable going into the TV or do I end up with both coming in.
thanks,
Richard

It will be down to personal preference. Currently by using the terrestrial aerial you are receiving freeview, by adding the satellite dish at a later date will enable you to watch freesat. There will be an overlap in the channels available from both platforms but there will also be a few channels that will be unique to each platform. Having both connected will give you greater choice. So in short no the satellite feed will not replace the terrestrial feed, both will be required should you wish to receive both services.

I think you're better off using Persil for washing TV
(Sorry couldn't resist.)
Yes you will have two cables, the cable from the Satellite dish needed for Freesat will have a different connector to the cable from your terrestrial antenna and will connect to the port labelled 'Satellite' on the back of the TV.
(If you are concerned about having multiple cable runs then ask your installer to consider combining them. This obviously depends on the relative locations of the antenna and dish and you would need a splitter behind the TV to provide it with the separate connections it needs.)