Hi Cazza
My DS is 4 months today and we started sleep training at 12 weeks. We started with pat/shush but this seems to have evolved into PU/PD as Zander has learnt to self-soothe.
This is what I do (I say 'I' because DH doesn't have the will or determination to do this - a bit like your DH he's quite happy to 'go with the flow'. Unfortunately I'm slightly obsessed with BW but with good reason as it's worked great for Zander!).
Zander sleeps on his side and likes to suck his fingers. So I say 'you're going to sleep now, see you when you wake up' and help him get his fingers in his mouth and lay him on his side. If he goes straight to sleep or is calm then I leave the room. If he starts to cry (and I mean cry like he needs help rather than fuss or cry like he's settling) the I pick him up and hold him vertically and say 'it's only sleep, you're frustrated because you're tired, mummy's here to help, it's sleepy time Zander' etc. etc. over and over again. (This helps to keep things in perspective for me too - when I was doing pat/shush I'd often be crying at the same time!). When he calms down or starts fighting against me by arching his back or kicking his legs or headbutting me (!) or after a couple of minutes I start again with 'you're going to sleep now' and lay him down again in the same way. If he still cries then I repeat the process but what I find is that all of a sudden just when I think he'll never stop screaming I put him down and he goes out like a light and it's all over!
Because we started with pat/shush and Zander knows how to sleep independently PU/PD is usually pretty painless for us. He's just woken early from his first nap this morning and it took me 20 minutes to get him back to sleep. I imagine if your LO is used to something different it may take longer and be more difficult to begin with (she may also regress just when you think you're getting there). It really does work though if this is what you decide to do.
If I can help anymore feel free to come back or PM me.
Kelly x