You should listen carefully to what WWW has to say.
I managed to get an airline job with 270TT but I was VERY LUCKY and managed to get in at just the right time - it wouldn't have been possible 6 months before or after I joined.
If you go to one of the big schools and shell out all that money for an integrated course plus rating then you might be OK (provided you do well, keep friends with them and have the personal qualities too). With modular training you might need to look at an FI rating too. I went modular and never instructed, but people I know who did really enjoyed it and felt that it really improved their flying. At 18 you shouldn't really feel under any pressure to do it all really quickly!
Good luck. As others have said though, your family connections could be a winner for you - for advice but also for good people to call for a job when you've finished your training....