Yes to all of that TM, plus BRC.
OASC first.
Then, if you have no regular or RauxAF non-commissioned service, you have to do the Basic Recruit Course at RAF Halton, 15 days straight (I've just completed mine), where you do first aid, CBRN, weapons. You will have to do some General Service Knowledge before that as you'll be getting a test on it directly you arrive at Halton. If you're coming in from a RauxAF Squadron the GSK and BRC should be organised by them.
BRC is element 1 of your Officer training
BRC provides you with the necessary qualifications to then start on the ROIT.
Thatstarts with distance learning (two HUGE envelopes of info arrived through my letterbox whilst I was at Halton), during which time you should be guided by a mentor from your Sqn. Also during the distance learning, you'll attend 4 weekends at Cranwell. If you're successful in those, that's element 2 complete.
Element 3 is a 14 day attachment to a regular courseincluding a 5 day field exercise. Final day is certificates and Champagne.
The age limit for Officers is currently the day before your 56th birthday (if you've had previous military service, not sure otherwise, but maybe 50), counted AFAIK from the date of your pre-Cranwell P2 interview.