Bit of gender role reversal going on here isn't there?
We had a heating problem a week or so ago, signed up to british gas homecare, they sent the most incompetent person I've ever met, after repeated visits still not fixed and I was getting hacked off with losing fees from all this time off so in the last week I've learnt everything there is to know about domestic heating installations and just fixed it myself.
You need to replace your stopcock, so turn your mains off from outside. There will be a little 4" square hatch in the ground most likely on the pavement that you can flip up, you can either buy the tool to shut it off or make one out of a length of wood (cut a v-notch out of the end and nail a cross-piece to the top to act as a handle), my recommendation is the second.
Run the
cold water tap in the kitchen to make sure you have just stopped the mains - all your other taps will feed from elsewhere, must be that one - turn it off afterwards. Assuming you have compression fittings on your broke stopcock (i.e. not soldered joints, in which case you'll have to cut the pipe top and bottom, leaving you with a longer gap to fill and obviously no going back so get a plumber) grip the valve with slip-joint pliers or similar (so as not to stress the pipe) and undo the nuts with an adjustable spanner. Slide the nuts away from the stopcock and pull the pipes out top and bottom. The water in the pipe will drop out now so have a towel handy.
Get yourself down wickes or similar taking your broke stopcock with you. Taking the olives off the pipe would be a PITA so buy the exact same one as a replacement - you are going to save a lot of hassle by using the existing olives. Also get some PTFE tape. Wrap the olive with just a little PTFE tape and just straight replace the stopcock. Cross your fingers and turn the mains back on. You've just saved yourself £100+
.
So.....what sort of heating system do you have, open (vented) or sealed, and what sort of boiler do you have? Next thing will be to fully drain your system down. You will need to stop it refilling from your cold water storage tank, in an open system there is likely a valve between the cold water tank and expansion tank to let you do this, otherwise, tape up the ball valve in the expansion tank. Get yourself some garden hose, clip/tape this to a drain-off valve and put the other end down an outside drain, then drain down the system. If you don't have a drian-off valve, you'll need to take off a radiator, which will be messy. Don't get any of that water on carpet, it will ruin it. But once the system is drained there will be no more leak, you will still have water to all your taps and toilet, but obviously no heating. Don't worry about pipes freezing, we just had a week with no heat and nothing froze inside the house.
So how exactly is the boiler leaking, take the cover off, can you see damaged pipe, heat exchanger, or what? That is where it can get expensive...