I installed a Texecom Premier in my house a couple of years ago having never touched alarms before. Was mostly pretty straitforward, but a few issues cropped up and Texecom support were very helpful.
A few tips from my experience:
If you use the higher end PIRs you only need to take the DC supply and alarm cables back to the panel, and set the resistance / type of PIR at the keypad, if you use cheaper ones you need a resistor in the PIR. I used T-EOL for most of my PIRs which were dual-tec, but needed resistors in the "pet-friendly" ones I installed in a couple of rooms downstairs.
I wired in two bell boxes as I wanted one on the front and one on the back of the house. I had some problems but can't recall what just now so send me a PM if you have this issue and I'll get back to you. You can also install the bell boxes to grade 2 or 3 and the wiring is different.
Use 8 core cable even if you don't think you will need it - it doesn't cost much more, and gives more flexibility (i.e. to wire the sounders to G3 I think you need 8 cores).
The first time I set the alarm and tried to dis-arm it, it refused and said something about needing a key-fob. If you have a keypad without this you can't and I had a brown trousers moment thinking the alarm would go off - it didn't but there is a setting to disable that. Also if you are not having monitoring disable anti-code reset.
Finally, be aware that if you state that you have an alarm on your house insurance, unless it is always set when you're out, the might refuse to pay up. For the tiny reduction in premium I wouldn't bother - but I think it's worth having all the same as I am sure that professional criminals can easily tell the difference between a bell box connected to a functioning alarm system and a dummy with a flashing LED inside it (unless you get a Yale DIY which has neither!)
I enjoyed installing the alarm and it works well but be prepared for some head-scratching moments. Let us know how you get on.
Richard