My aerial is 2 aerials both a UHF and a VHF coming into a splitter, This is amplifified as well as we don't seem to get any signal without the amp.
What kind of amplifier do you have?
A masthead amp at the aerial or distribution amp at the TV end of the coax? They perform different functions. The mastehead amp amplifes the signal at the antenna. The distribution amp amplifies all the signal plus crap at the TV end of the coax.
Obviously the sensitivity of the Magic TV Tuner is much less than the TV's tuner or you would be getting channels already.
Try running the UHF aerial direct to the Magic TV. If that doesn't work then try a Masthead amplifier as well. The magic TV and your TV don't need the VHF aerial connected anyway for Freeview.
Make sure the UHF antenna and coax are in excellent condition and well away from the VHF and other obstructions. Just having the VHF antenna on the same pole can be sufficient to downgrade the UHF signal drastically in weak signal areas.