Ford KA heater blowimg cold and brake light flickering

Hi,
Last year, my jester started blowing cold. If I turned the engine on and off it would work again, until one day when it gave up all together. At the same time, the hand brake light began to flicker, this started when going down hill so I thought it was the fluid, but it didn't need filling and then as the heater broke, the light was on almost continuously.
Then I has a crash where I was hit in the rear end..... the heater and light were miraculously fixed!
But now, a year later, its come back. My heaters off and the lights there.
Only had my mot a couple months ago.

Any suggestions would be ace, I can't really afford garage prices if its something not too bad, and although i havent got a clue, I have an ex-mechanic friend who I shall rope in!

Thank you!