Carnations and dhalias.

Yes you can. Sarah Raven increases her stock by taking cuttings in spring too BBC - Gardening - Basics - Dahlia cuttings

They are tricky .. Pinks are much easier to grow. The British National Carnation Society :: BNCS: Carnations - Beginners Guide

I grow pinks, and find some are much easier than others. I have some on the allotment that I do nothing to, and they have formed a massive clump and flower loads.
I find cuttings really difficult, even though the principle is easy ... I think mine are always too wet.
Anyway, here's a guide: BBC - Gardening - Plants - Pinks, Dianthus

I never had any luck with carnations, pinks etc till I came to my current garden where the soil is very well drained. My favourite Mrs Sinkins grows like stink and I get loads of cuttings from her every year (and I'm usually rubbish at cuttings!) Have you tried rooting pips in water 2 sheds?

Braco2Zero, carnations like a bit of lime. Depending on what your soil is like you could lime a patch for them but I find they do well just planted beside a wall or in some stoney ground. They don't like acid soil.

Two years ago I sowed some perpetual flowering carnations. I planted some out last spring and in the autumn, more of an experiment than anything else, I potted up a nicely scented and coloured one into an 8 inch pot. It's in my cold greenhouse now and still in flower........so they are perpetual if treated right.
I will make more of them this year, picking out the best ones and potting them up as the experiment has seemed to work.

My neighbours Dahlias are starting to sprout from there corms now he told me today.......mine are still dormant thank goodness!

Dahlia's are easy from cuttings do exactly what you said, pot them up and give them a bit of bottom heat and they'll soo start to sprout. WHen they have 3 pairs of leaves take them with about 2 pairs of leaves on leaving the bottom rounded leaves on the tuber to give you two more cuttings. you need an open gritty compost ( I use 50:50 either sharp sand or perlite & soiless). If you can put them in 24 cell packs and cover with a plastic propagating cover It'll keep them moist and pot up as soon as they have a reasonable root system. then keep potting them up otherwise they'll get a check and won't do as good.

Carnations - depends on what sort you've got. I grow Pinks, Border carnations and Perpetual flowering Carnation Pinks will do OK for a couple of years but really need digging out then as they grow woody and sprawling but you can take cuttings (pipings easy enough) Borders and PF's are best grown new each year to maintain vigour although they are good for 2 years. These are relativley easy from either pipings or as layers. they do need support however and PF's will also need a frost free ( or a bit warmer really) G/H if you want flowers this time of year. Unfortunately not all carnations have scent so pick them with care.

Can't comment on Chaubaud carnations as I've never grown them.

thanks for the info on carnations 2sheds my mum loves them and we are gonna try and grow some this year and the carnation site is fab