NMP
It is perfectly legal for you to use the ILS free of charge without telling ATC.
If you are flying visual circuits at that airport there is nothing to stop you dialling in the ILS and using it for localiser and glideslope guidance for your visual approach to landing.
Apart from helping you with the glidesope you can also practice keeping the needles locked. But as part of a normal circuit.
Flying a visual join at an airport I will often dial in the ILS to assist with centreline and glide positioning and I would call that good practice.
Pace