Yes, well, (he says cracking his knuckles...)
I have been messing around with Lambda's for the last few days, and have a few bits and pieces to report.
On the 145 1.8 TS (same on the 1.6 apparently) the lambda is easy enough to replace as it's on the top of the exhaust pipe before the CAT. I think it needs a 19mm open-ended spanner to loosen it, and can be tough.
Don't worry about the TDC sensor, I think I was a bit off the mark with that. Go for the Lambda. The guy who replaced mine said that they seem to go on the TS engines after 2 yrs...!
As for the wiring, if 'Just Lambda' supplys simply the sensor and a couple of feet of cable, then it will need to be spliced. If it comes with the connector installed, you may still have to splice it as the gap between the bulk-head and the back of the air intake is tight to say the least... and you may still have to cut the wires and splice anyway!
The one thing about doing this job is that you have no way of knowing that the Lambda is working. You must bring it to either the NCT (MOT) center for a test or a local garage...
And finally, you don't need to reset the ECU. It is all figured out by itself.