However, I always use Wifi in the house.
Am I going to see a significant jump in speed when using it over wifi?
It will depend what version of Wifi you are using and how good the connection is. Some of the earlier versions operate below the speed of FTTC and it wouldn't take much to cause even a newer version to drop down to the point where it masks some of the speed gains from FTTC.
You need to find out what speed you're connected to your wifi point at. Tell us that and we can answer your question
As Andrue says the broadband may not be the bottleneck.
If I had ADSL2+ even running at just 10Mb but was using 802.11b wireless then I would only be getting throughput of probably 5 or 6 Mbps - so increasing broadband connection would make no difference.
Also, again as Andrue states it depends on the conditions. If the router is in the living room and you are using it from an upstairs room then it is quite possible that the building structure and interference (from other WiFi or even household appliances) the throughput of 802.11g or 802.11n could both be reduced to a point where you could not attain the full speed of FTTC.
So, checking the actual throughput of the wifi is essential. Easiest way could be to just do a file transfer between 2 devices on the network - that would give a good indication of the real world speed of the wifi discounting issues of broadband bottlenecks.
That is an excellent comparison. Shows up the problems with various methods of connection and why some people are going to be seriously disappointed with throughput when they have bought a fast internet connection.