A couple of things, you might want to consider investing in a dish and receiver to get HD broadcasts, but if you only want to optimise the current set up, you might want to check the dish alignment. Watching a standard definition picture on a HD TV is probably always going to look rubbish though. If you paid someone in the UK to do it for you they would probably be charging an arm and a leg, perhaps see if any mates have a signal detector, or you might invest in one, though it's possible to do the job as well with just a compass if you have the knowhow.
You can find websites giving advice on how to do that if you are going to try it yourself. If you have an iphone, you can get an app that shows you the position of the most common satellites. There's more than one to point the dish at as well, for example Astra 2 at 19.2 degrees gives the UK HD channels, but is a weaker signal than Astra 1 at 28.2E degrees. Here's an example of a site where you can find out more about this stuff:
http://www.uksatellitehelp.co.uk/2007/0 ... ulator-v2/If you fancy viewing channels on more than one satellite a good robust motorised arm is worth installing.