Hi there Pete, and welcome.
I can only answer a couple of your queries (I don't own a Kangoo), but I'm sure someone who does will be along quite soon to pick up where I leave off.
A squeaking sound may be something as simple as a drive belt (read fan belt, in old money) which needs adjustment or replacement - or it could be a water pump which is on its way out. Naturally, the belt is the easiest (and cheapest) to check out of the pair.
A service may not necessarily have been missed out (the book might not have been stamped), but you can never have too many services (in my opinion) and at least you will know for sure, when it was last carried out.
As far as the rough running is concerned - it may just be normal for the vehicle - as you say, its the first diesel you've experienced (they are rougher than petrols, especially V8's
), and vans don't have so much in the way of sound insulation - it may be nothing at all - whoever carries out the service can investigate further if you feel it warrants it.
I don't know about the timing belt complexity (or not), I don't think its a Renault-only job though - many independents would be able to handle it, I'm sure. It would be a good idea to combine this work with the water pump change (if it turns out to be on its way out).
All the best, and look forward to hearing more from you in due course.