Installing satellite TV in England, UK

Change back to the Sky receiver.   If all is well, perhaps with an improved signal then your problem is with the new receiver.   Read its manual and work out how to tune it and change frequency bands and polarisation.

If there are no signals with the Sky receiver then the problem is with your new antenna installation.  Is the LNB cable properly connected ?  The centre pin of the coax should stick out 2mm above the rim of the F connector and should smoothly insert properly into the LNB socket.  The coax outer braid must make good connection as well. As a rule I would suggest new cable in every installation.  Use self amalgamating tape on the outdoor connector to seal out moisture. This is important since cheap cables often have an aluminised mylar tape as the outer conductor for the signals and the aluminium film quickly degrades with the slightest moisture.

Have you set the dish pointing and optimised the polarisation angle ?  You will need a meter or the signal display from the receiver to peak up.  As a guide for the elevation angle go to this page: https://www.satsig.net/maps/satellite-tv-dish-pointing-uk-ireland.htm  You will need to peak the polarisation by measurement.  Turn the feed/LNB polarisation either way till the signal is degraded by exactly equal amounts and then halve the angle.
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Best regards, Eric.