Although I used to work for FCUK (when air2bob), I would recommend to go for Virgin if you/your friend have/has the choice. FCUK in Bristol is a small base and the 767 do not fly from there therefore it's no good for long-haul. Finally, working for a charter airline is really hard work! The money is not that great either and nightstops are seldom.
VA is probabily a better option if you/she wish/es to travel as you get to stay 36h/72h (sometimes longer) overseas. VA's contract is PERMANENT which is a very important thing nowaday!
Charter contracts are often seasonal or temporary and only a few people(depending on the winter business) receive permanent contract at the end of the season, which generates bad competition amongst new employees (not all, thanks God!).
If money is a major, then keep looking around as there are better contracts available, to mention a few: BA or Qantas UK.
Don't get too scared when checking the basic salary as allowances are usually a very big portion of the salary and they are very difficult to evaluate until you're working.
Hope it helps!
FJ