Keygrip
In the UK times are changing. At the school I work for (London area) they are always short of instructors. The trouble with using part-timers is that you can't rely on them to work other than when they feel like it and you can't shake the Big Stick quite as much as you can with full-timers.
If you are a competent FI (UK) with a few hours under your belt, the schools need you right now more you need them. I work for a busy school in the London area and they are always short of instructors, particularly as fewer and fewer wannabe Nintendo jet pilots want to spend £5-8k on a FI rating when they can pay for a type rating instead and "fly" for an airline with 200 hours in their log books. With the advent of the new Multi Pilot Licence, light aircraft instruction will be even more irrelevant to transport jet operations and even fewer will choose to mark time this way.
This is good news for those who really want to teach for living and ultimately for the students as well.