This is fairly standard practice at the larger gliding clubs.
The successful applicant will get several hundred hours "free" flying over the season in return for their labour. Board and lodgings are usually included. You get to do hundreds and hundreds of takeoffs and landings (probably 6 or so an hour) and get to fly all sorts of interesting aeroplanes. Your stick and rudder skills will probably never be as good again!
300 hours x £80.00 hour = £24,000 free flying!
Dependant upon the weather, 300 hours could be very conservative - you may well get loads more........