I think you really have only 2 options:
1. Tell your friend to stuff it, and tell him
to train hard and eat right. I mean he's VERY
skinny so he shouldn't have much trouble in
putting some mass just by eating more
and training hard. This alone can give the guy
6-7lbs/month easy for 2-3 months.
or, if he's a typically stubborn brit.
2. AS. Thats ANABOLICS NOT ANDROGENS.
I can't stress how bad he's going to feel when
he starts getting acne, bloating etc... from
the androgens. Plus, he's in MODELLING.
You really can't get a more superficial job.
I know some models personally who I know juice
and I sometimes train with.
This is what they normally use:
BULK-UP:
1. EQ+winny. or Deca+winny if joints are an issue.
Cutting:
1. Primo+Anavar or EQ+primo or anavar or winny
Novaldex or Arimidex depending on water retention.
They rarely use proviron.
Thats it. No fancy business at all.
Pretty simple really.
Godspeed