Money has jumped up a lot for all ranks including SFI's.
Part time is not an option for new joiners as it's not a contract option until in the Company.
The Company doesn't 'offer' part time so to speak but if you do all the leg work and find a pilot to buddy up with and present a fait au complet to them they tend to go for it but if you just rock up and say I want part time they say go and find someone to share with and then come back.
Most people who can find someone (in Stansted anyway) I think have it.