We might need some more information here because it's not clear what type of equipment you were using before the problem arose. Were you already getting decent Freeview reception or did you only have analogue reception?
I'll assume that you already had digital TV, with an aerial feeding to a Freeview box, which in turn fed a signal into the back of your TV. My second assumption is that you were getting good reception with that set-up. Lastly, I'll assume that your reference to a 'DVD player' means exactly that, and not a DVD
recorder.
If all of that is true, and introducing the DVD player into the 'chain' has ruined your reception, the solution is obvious: Take the DVD player out of the chain.
No, I'm not suggesting that you throw it away! Instead, go back to your old line-up (Aerial>Freeview box>TV) but insert a Scart switch box between the Freeview box and the TV. (So the line-up is now Aerial>Freeview box>Switch box>TV). Then plug the DVD player into the other side of the switch box.
Maplin Electronics sell several suitable switch boxes, e.g.:
http://www.maplin.co.uk/Module.aspx?ModuleNo=9 7936
but you might find something suitable cheaper in Asda (or possibly Tesco Extra).
If I've got it wrong, and your line-up is different from that which I've assumed, please post again with further details. However, if it comes down to using a better aerial, this is the model which is most frequently recommended here on AB (as well as in several technical magazines):
http://www.maplin.co.uk/module.aspx?moduleno=2 2523
Chris