I think you have to take the stance that you, as an unemployed pilot, should take whatever jet job is offered to you as quite frankly whether it is Airbus ir 737/757 you are getting an opportunity many have and would fight tooth and nail for.
Whilst I can appreciate you might prefer one type, I dont think you would be looked upon too favourably if you stated you only wanted Boeing or Airbus for example.
I can totally understand your stance as I thought the same, but the way to look at things is that once you are the other side of the recruitment fence, you have a few more options. i.e. 1000 hours on jets (for example a year and a bit) you can move to where you might want to be, rather than having been put by CTC and 9 times out of 10 once you have this experience most operators you migrate to with experience will pay your type, as you are generally moving up the ladder most see it, although I cam quite happy where I am at the moment!
In terms of paying for a type rating whilst waiting you will certainly preclude yourself from the scheme. CTC certainly want to asses you using their own instructors, through their own systems and practices.
I had a friend that was in the same boat (ish) only he was in the pool and was offered a job on a Turboprop whilst he was there. He asked CTC if he went there could he keep his place, they said not. Reason being you as a CTC cadet are expected to start at very Short Notice. Mine was Call on Friday for a Monday Start. Hard to get a job which will keep the wolf away from the door and allow you to leave with that kind of notice, but can be done if you are straight with them and dont use any of your holiday. Again, that was what I did, used my holiday to cover my Notice period and explained this from the start.
All in all it takes a while, but you are straight onto a jet, and not had to shell out the 20k for the rating. There are pro's and cons's but I have got a 737 rating out of it, and will start my Airbus course this Aug not even having had 1000 hours on the thing! Not because I am anything special, just with everything in this business in the right place at the right time!