concessions:- you will get 6 confirmed tickets for either £35 or £50 each (sh/LH) after six months service, then on the 1yr aniversary of your start date you will get £500 off any brochured holiday including city breaks- so doesnt have to be flying on Tfly could be on Virgin/BA etc... the £500 goes up in year 2,3 etc.. but dont quote me on what it is. Not to clued up on the new concession scheme!
As for part time, yes you can apply for it, and be considered for it after 12 months however at a large base such as LGW you will struggle I have just had my Part time rejected for the 2nd time this year.