Family of 6 hoping to activate skilled migration visas for Perth in April. Kids aged from 9-14. Any suggestions on affordable accommodation given the expense of airline tickets? What's the best way to get a real feel for the area in just 2 weeks? Hoping to book by the end of the month before flight prices increase again.

Virtually the whole of April is school holidays with 3 public holidays in the month.

That means accommodation is likely to be expensive. I guess you are coming then because of UK school holidays though?

We are required to activate visas by May 13th and don't want to take kids out of school. Any suggestions on cheapest accommodation, ie. house rental or hotel?

Here a place you can check for somewhere to stay
http://www.stayz.com.au/accommodation/wa/perth?view=map

I suspect you will struggle over the Easter break as the previous person stated.
School are closed Friday 6 April – Wednesday 25 April - Would you not prefer to visit schools and get something organised for the kids while you are here? (Just thinking out load) Could you not come after 25th April and have an idea of the area and the schools you are interested in viewing?

Good luck.