Since you mention an igniter I'm going to assume a gas furnace. So start by turning off the gas. Then disconnect everything else other than the power in and the thermostat wiring.
Now turn on the thermostat. If the fuse doesn't blow, reconnect one thing (like the igniter) and try again. Repeat until something blows the fuse.
Since you have isolated the problem to the igniters, I would try just replacing one or both of them. That's probably cheap to do. If that doesn't work, then you're probably looking at replacing the control board.
First, be wary of the two big capacitors. One is the large "beer-can"-shaped component against the inside wall of the enclosure, and the other is the smaller, silver oval-shaped can right next to it. These can hold electrical charge, and could hurt you. You'll want make sure that they're discharged.
Once you unplug the unit, wait a few minutes for the caps to discharge on their own. Then, get a piece of insulated wire, or pliers with insulated handles, and short out the two terminals on the top of the cap. It may make a good spark, which is why you're doing it! Better to spark through the wire than through you :)
There's a third cap on the pcb (big silver unit with a wire coming out either end), you should probably discharge this one, too.
The white connector up top will be easy. Generally you just grab all the cables together and pull it out. There may be a latching mechanism holding things together that's not visible in the photo.
At the bottom of PCB (going by picture orientation), look at the black and brown wires that are connected to the board. The are using "quick disconnects", which can get to be fairly tight. Grab the connector (not the wire), and rock it back and forth (the long way) as you pull on it. Needle-nosed pliers might help.
Those wires have wire nuts on them too, but I would leave them alone. Once you are finished, give each wire coming from the wire nuts a firm tug, to make sure they haven't loosened up.
Oh, and I recommend marking the wires before you disconnect them. You can make small tags on the wires using masking tape.
Should be pretty straight-forward. Good luck!
Best Answer
Hot surface igniters are fairly universal it they look the same and have the same voltage. For example the igniters on this side of the pond they are usually 120v so depending on your area yours may be a 230/240v. I have had some bad luck with after market igniters coming cracked or with a fingerprint on the igniter in a sealed bag. Make sure not to touch the element any body oils like a finger print can cause a very short service life. Since you have some room the one you reference if the correct voltage should work if it looks the same.