how can I check if a phone mast is having any work done in my area/???

3 have a status checker, otherwise call your provider

Vodafone too

You already have a thread http://forums.digitalspy.co.uk/showthread.php?t=1971127

If you know the physical location of the mast, then you could try taking a look at it.
I had no signal a while back, Three said everything was OK, a physical check and asking someone said otherwise ( roadworkers had dug up a cable)

go to the mast and use a app like Network signal info to see if it is live or not, if you dont have an app put your hands over your phones aerial and if you still have full signal id say it is working!

Since when did covering the aerial change the signal?

iPhone 4 xD https://www.youtube.com/watch?v=BoTepMX3x5k

But seriously, I don't know if the death grip still exists in newer devices...

Dial *3001#12345#* on an iPhone. If you get a reading -50 to -65 near the mast it's on.

Yeah I know that but NOW there's no issues, and it wasn't everyone even back then, I've had iPhones since the old 3G and never had a problem