X-Channel checks should be logged as P1 to you for the last X minutes from FIR boundary to landing in france.
ILS approaches can be done under VFR, so they are perfectly possible with the UK-FI as safety pilot - you are not under IFR so the "trainee" is P1, and not P/ut, for the duration of the french-FIR bit.
Alternatively, if the FI is also an IR holder, he/she can log P1 for the french ILS approaches and you could do them under IFR (but log nothing)
Not a real issue unless you only spend 10 seconds getting from the UK-FIR to the french FIR and then spend a lot of time inside french airspace...
But what the hell: If we're going to advertise breach of copywrite on a public BB, we may as well log whatever we like in our logbooks