First things first. Get VIDA, it provides you with a load of intructions and fault tracing possibilities.
VIDA is independent from a DICE!
Which means, you can use VIDA as your repair handbook, no "need" for a DICE.
Get it and check for yourself, the explosion drawing provided by stuart bowes is from VIDA.
That should give you a better insight, where parts are located and how they work together.
If you want a reader, go with one from Cheshired5 (Simon) here from this forum. It costs around GBP 100.- (DICE or VCXNano) and you would get VIDA together with it, and most importantly, Simon provides an excellent support for the products he sells!
The iCarsoft readers are more expensive, but you can probably read more than Volvos.
I wouldn't go that way, if you have a Volvo, get the tool for Volvo, not something generic.
And if you stop using Volvos you can always sell it on, prices are nearly stable.
Give Cheshired5 a PM and talk to him, I'm sure you will find a great deal together.
Check his thread here:
https://www.volvoforums.org.uk/showthread.php?t=256681