Hi everyone, I'm new to JAL international and shall be flying LHR-HEL-NRT-CGK shortly （LHR-HEL codeshared on AY metal) with approx 8hr connection in NRT.

1) Can I assume that I'll be able to check through my luggage from LHR all the way to CGK? (OW website suggests this should be possible as the connection <12hrs but check arrangements for individual airports...)
2) During the connection in NRT I'm planning to leave airside and hop into Tokyo for lunch (am familiar with Japanese public transport/NEX and language so know where I am going and that it is doable). I imagine I'd technically be breaking rules leaving my checked luggage behind etc, but in practice would there be anything getting in the way of executing my plan? (assuming I will have preprinted the ex-NRT boarding pass)

Thanks!