Budgie,
Having recently seen a presentation by a senior bod from the Aircrew Retention scheme, I understand that in the near future all new pilots will be accepted on Permanent Commissions only. So it may be worth deciding you want a PC anyway before they force to you to "take it or leave it".
I definitely agree with Spugs - finish your degree off before joining. Having already spent 2 years at uni you will be nowhere if you quit now - you won't have the youth of the post-'A' level entrant, who gets to Flt Lt aged 23-24, and you won't have the promotion rate of the graduate, who also gets Flt Lt at 23-24. You'll be more like 26!
As regards flying pay, under the current system you become eligible after 72 weeks of flying training - for my ex-JEFTS colleagues this has worked out as being about 22 months after they completed IOT. Which roughly coincides with the Flt Lt point for a 3-year degree graduate! Flt Lt + Fg Pay is about £32k, not at all bad for a 24 year old... think about that next time you have an essay crisis!!!