The handbook of my Volvo FM12 mentions a 30amp supply for a coffee maker and suggests that the wiring is in place in the loom. The fuse is in the box, are there are pair of wires somewhere that I could pick up to run a 24v kettle on a cig. lighter / Hella socket.
I have given up with a 12v kettle as the supply to the cab is only 10amp and a low power kettle takes about a week to boil.
it maybe worth ringing a uk based volvo truck dealer or volvo service workshop. if the wires are there like you say then all that would be required is for it to be connected to a new socket,its the best advice i can offer, best not to DIY in case you make a mistake and blow the electrics if your unsure.
volvo is a good place to start. once you have got the info you need, get prices and shop around for the part and fitting, you may get it cheaper than the dealer 
I have asked around at the dealer, but never found a huge amount of help. Just wondering if someone here might have the answer.
Why don’t you invest in a small camping gas cooker, I have one thats in a case and stores away, don’t take up much room either.
When I got my last truck, an FH Volvo, the sales guy gave me a Volvo coffeemaker as a present. He hadn’t had it fitted as he wanted to make sure I wanted it before doing so. When I confirmed I did indeed want it 
he got the electrician to fit it, it took him all of about 15 minutes to mount the bracket an connect it up as the wiring was already part of the loom. In both the FH and FM it sits just to the right of the passenger seat on the floor, the only difference between the two is the mounting bracket, and the wires are just behind that area of the dash.
It is going to Mc Truck & Bus for its first birthday and MOT, I’ll ask them again if they can locate the wires for me.
he wanted to make sure I wanted it
Did he really need to ask with a name like Coffeholic 
Coffeeholic:
When I got my last truck, an FH Volvo, the sales guy gave me a Volvo coffeemaker as a present. He hadn’t had it fitted as he wanted to make sure I wanted it before doing so. When I confirmed I did indeed want it
bet he wouldnt have given it so quick if he knew you was only going to have the truck a couple of months.
jessicas dad:
Coffeeholic:
When I got my last truck, an FH Volvo, the sales guy gave me a Volvo coffeemaker as a present. He hadn’t had it fitted as he wanted to make sure I wanted it before doing so. When I confirmed I did indeed want itbet he wouldnt have given it so quick if he knew you was only going to have the truck a couple of months.
It was actually a gift for sorting out a buyer for my old truck, saving them doing any work. 
On the Fm/FH all the looms are standard this includes wires and milti plugs for spots,fone,cb etc all you have to do is find it and fit switches/plugs in the hand book for our FH (04) it give the fuses use and if you can follow the wiring diagram your find them