How do I change thermisters in a Feroli Modena 80e?

I've just been told that the thermisters on my Modena 80e need to be changed as the boiler heats up and cuts out, both on the radiators and the hot water, and then heats up, cuts out etc (which is very exciting if you are in the shower at the time).

I've read lots of posts suggesting that this is a well known problem...

Is changing the thermisters something I could do myself? I've also been recommended that the venturi gets changed too... again - is this something that I can do?