He's agreed to evrything but then moves goal posts around, for example says I can't have kids as so busy but then is in the pub for a quick pint etc when I ask he says I'm controlling him. Booked to go on hols for a week with dad with no consultation and I said no as I can't cover childcare as I work and he didn't chevk, I'm controlling as it's only a week and it's unfair etc. He'd go spare if I swaned off for a week with no notice!
It sounds a bit petty
It's not petty at all OP, but I bet he tells you it is.
In between telling you you are "controlling" for daring to point out when he reneges on yet another promise.
His words are designed to mollify you while he continues doing whatever suits him - & to hell with your feelings, or family life.
You are not "petty" to observe that his words are so different to his behaviours. But ... he's a serial liar, isn't he, so par for the course ...
On a plus side and to be fair, drug tests are clear and his blocked the woman on social media and phone etc but obviously thats easy to unblock when I'm not around.
Not taking drugs or shagging other women is a very low bar to set.
And you know he's only holding off to keep you sweet until ... the next time. I imagine that will be your fault too. Cos you know, you are such a controlling old dragon that he has to take drugs & chase women to be able to deal with the stress your (entirely reasonable) demands put him through ...
The couseller implied he gaslights, eg asked for space and he rnag evry single day said he'd kill himself if I didn't speak to him etc and asked me read some things around this.
She's spot-on. Stick with her - JUST you. Don't take your waste of space with you - couples counselling is NOT recommended when one of the pair is abusive. (btw, that's not you!)
www.amazon.co.uk/Why-Does-He-That-Controlling/dp/0425191656?tag=mumsnetforu03-21
www.freedomprogramme.co.uk/online.php
Sorry for the rambling post but feeling conflicted
You ramble on my dear, It will help you start to sort it all out in your mind. You have been living in the twisted dynamic of cognitive dissonance caused by him saying one thing, but doing another. Of course you feel confused & overwhelmed.
Single parenting etc feels very daunting to me, which I know I will manage okay if I must
Yeah but no but ... 
Imagine making arrangements for your & your child's life that get set in stone because you are making them with solid friends or professionals, not this flakey twat.
Imagine the smooth running of a household without someone actively sabotaging your career & comfort by arranging an impromptu holiday & dumping the childcare arrangements you thought were meant to be solid.
Imagine a home life free of constant lies & manipulation.
Imagine the atmosphere you can create for you & DC when you are not being lied to, gaslit, cheated on, & constantly let down over "promises".
Imagine how you will feel when there's nobody in your home calling you "controlling" every time you make a reasonable request.
Imagine the simple relief of not having to constantly police & maintain your boundaries, because there's nobody in your home who delights in trampling them.
You are being taken for granted, used & manipulated.
He's shown you who he is, & that he has NO intention of stepping up as a parent, let alone a decent partner.
The relief you feel when you fuck him off & no longer have to tolerate his bullshit will be immense.
Fuck him off, OP!
I know it's easy to say, but you sound strong, bright & resourceful.
Take your time, chat it all out with your counsellor for some handholding, & start taking the practical steps you need in order to get this unpleasant man out of your home.