Here are some guidelines from someone whose son is there,
as well as an address at the bottom of the page.

I find the easiest method of sending these parcels is to use a large padded
envelope but any form of parcel is fine as long as it does not exceed 2
kilos. They are very strict on this. Tape it up firmly, stick on the
label and take the parcel to a post office where it will be sent free of
charge by BFPO Mail. Parcels generally take about 5 days. Please do
write any encouraging message on a Christmas card for your soldier but
please sign your cards by Christian name only and do not give your address
as we do not want any obligation regarding thank-you letters.

Lots of people have asked what to send. One of the main elements of this
scheme is to provide a bit of variety. Therefore if you can use your
imagination to the full and think of a cross between Christmas stockings
and tuck boxes you will be on track. It is very hot in these countries so
please do not send things that melt such as chocolate. Alcohol (and
pornography!) are forbidden. This leaves plenty of goodies:

Biscuits, cake - homemade wonderful but bought wonderful too – but think
long life, like fruitcake, gingerbread or malt loaf. Anything in a tube,
vacuum pack or tin to perk up their rather basic rations is great - toffee
sauce, (M&S does a good range of savoury and sweet sauces in tubes)
condensed milk, salsa dip and cheese straws, cream cheese, fish paste,
chutneys, chorizo sausage, dried fruit and nuts, mint imperials, chewing
gum and everyone loves Jelly Babies. Soduko books and boys’ magazines –
Nuts, Zoo and FHM I am reliably informed are the most popular. Lip salve,
moisturiser, medicated talc and cotton socks are all good. They have to
drink vast quantities of water so any powder flavourings in a package like
Berocca, Vitamin C sachets etc. would be both light and immensely
appreciated. Finally our son particularly recommends old fashioned pick ‘n
mix sweets. Obviously the element of each parcel being different is a key
one and thus individual creativity would be much appreciated. Please keep
the contents within £10 for the sake of equality.

The customs stick on form is available at the post office when you post the
parcel.

The response from you all has been quite extraordinarily generous and
enthusiastic which makes this a lovely project to be involved in, and I am
confident that all your parcels will be most gratefully received. . Thank
you so very much.

Iraq: A British Soldier, c/o JI Branch, HQ MND (SE), Op Telic, BFPO 641

Afghanistan: A British Soldier, c/o Capt. S. Beattie, MBE, SO3 JI, HQ Task
Force Helmand, Lashkar Gah, BFPO 715