the US has no problem with shipping to Finland; however, it sounds like Finland may have a problem with it:
"Finnish authorities have decided that nicotine cartridges containing less than 10 mg nicotine, and e-liquid containing less than 0,42 g nicotine per bottle, may be legally brought in from other countries for private use. If the nicotine content is higher, a prescription from a Finnish physician is required. From a country within the European Economic Area a maximum of one year's supply may be brought in for private use when returning to Finland, while three months' supply may be brought in from outside the EEA. Mail order deliveries from EEA countries, for a maximum of three months' supply, are also allowed."
-- Wikipedia.
so, it says that eliquids can be "brought in" from other countries -- sounds like they're saying if a Finnish citizen physically brings
eliquid back home from another country, that's fine...but they then go on to specifically state that *mail order deliveries* from EEA countries are "also allowed" -- i take that to mean that mail order deliveries from *non*-EEA countries are NOT allowed.
in any event, it sounds like your friend can legally obtain his own eliquids -- and as bigtime suggested above, Liberty Flights in the UK is a great choice -- they are a large outfit, and are quite knowledgeable in such matters as you've described, so they should be able to answer any questions he has. in addition, they have great products and customer service according to many members here on ECF.