I can understand where the OP is coming from - the fees for using a service that is radiating energy whether anyone is using it or not, are disgraceful.
But in saying that, what you are proposing is not just illegal (as above poster mentions), but dangerous. Consider St Mawgan (Newquay) as an example. Sure, outside the 2.5 NM ATZ you're in Class G, but Ryanair fly their 737s within G airspace in order to reach the ILS... Amongst all manner of other flying machines you may encounter along the localiser/glidepath!
Best answer I think has again already been mentioned - find an airfield with an ILS, tell them you want to practice circuits/T+Gs etc, and just dial in the ILS freq and use that for the approach, with a safety pilot sat next to you for visual lookout.
