Two points (in the UK)
1 - an instrument procedure like an ILS can be flown VFR or IFR
2 - in G there can be conflicting VFR or IFR traffic, in D there can be conflicting VFR traffic which is called if you are IFR and which is down to you to see if you are VFR (remember point 1)
The G-EYES accident at Coventry shows these two points.
To the question, yes flying a pratice ILS head down (but not hooded) VFR with you 19 year old son as the competent observer is legal and sensible. Once you have your IMC you can due it under IFR in class D as well.
As a note - under a hood or behind screens you actually need a safety pilot (there is a bunch of detail around currency, class of licence, ratings, medical, etc. which IIRC is slightly more lenient than the rules for being P1)
Last edited by mm_flynn; 29th Mar 2013 at 09:58.