If you check back a few pages, I said about what you get with the alarm. I work for the company (ADT) but as you state smoke alarms are extra and yes you get fire brigade response.
Hope this doesn't read as me being rude sorry if it does
The systems are very reliable. The one you are referring to is the keyholder system. If you went directly through ADT it would be £99 but we have an agency that can sell alarms for us for a little cheaper.
I would say it is worth it depending what type of coverage you want/need.
We recently moved to lancing (my mum,dad and me) in our previous house we had a alarm for the house and I had a separate alarm in my bedroom to keep my brother out.
I will be putting a alarm in the new house. With the...