17leftfeet I empathise. Holidays can be expensive, particularly once kids get older and aren´t entertained by trips to the park or inexpensive colouring books.
I don´t know where you live but do look online and in local papers, even local radio or TV, for ideas about places to visit or activities going on.
Many cinemas have cheap entry in the mornings or on a certain weekday. Also check places like the leisure centre as sometimes they run free or cheap activities for kids and teens or have special deals on swimming.
Do you have a local library? They usually have some magazines, (also computers - if your daughters don´t have them at home this could be a treat for them), as well as obviously books to take out and read.
Can you let your daughters have friends over to watch a DVD? Or sleepover? At that age I could sit in my bedroom chatting to my friends for hours - but I know it´s difficult for your daughters if other friends have more money and suggest expensive outings.
Maybe start a routine of "pampering" - collect up all the nail polishes you have in the house and get them practising on each other (and you?) There are videos on YouTube for how to do fancy nail art as well. Ditto hair - practise some updos or fishtail braids or making their hair curly with a straightening iron (again, many videos to teach them how to do this).
Perhaps you could let them help you cook and learn a few recipes? Again, time can be spent by them looking to see which ingredients you have in the kitchen then finding recipes on the internet.
Download a TV series to watch?
Also you could think up some household chores for them to do that will take up some time such as washing and drying up, tidying their wardrobes, helping in the garden, going out to nearby shops etc. to do an errand for you, getting their uniforms etc. ready for school (or just activities like reading) to "earn" cash to go out with friends.
Look up some long walks in your area and pack a picnic.
Good luck with the job hunt; enjoy your summer.