I agree with the above - I think you need to make sure you agree how to discipline the children so that it isn't always good cop / bad cop, with you as the baddy.
My DH and I try to give the same punishments / rewards, and have also agreed on what is generally good / bad behaviour and worthy of praise / censure. That way we are both equal, and so are the kids, if you see what I mean. They know that certain behaviours will always get the same response, whether it is Mum or Dad watching them. We also have a few rewards / bribes worked out for DD1 (shes 3y 9m), like a sticker, phoning Daddy (when he is away overnight), ice cream after tea, etc etc. and reminding her of this seems to really help. Also, although she is complying with what I want her to do, she is also happy in the end because she gets something nice. And I do try to explain to her why I am asking her to do things, or why what she has done is naughty, so it doesn't seem like I'm just laying down the law (of course sometimes I do just lose it and shout a bit, because I'm not perfect).
Where it falls down a bit for us is that my husband works away for half the week. Especially the eldest of our two ADORES Daddy, and can be very naughty when he is at home, which we think is just an attempt to monopolise all his attention for the time he is here. When I tell her off and DH is away, she always cries "Daddddyyyyyyy", which really gets on my nerves TBH! I just remind her that if Daddy could see what she was doing, he would be very disappointed and cross too! So, I'm not saying we have it worked out perfectly, but being consistent between the two of us definitely seems to be the right thing.
I think that the parent who is there for less time is probably often the hero, and sadly that is something I (and lots of other mums I know) have to live with. After all, if Mum is always there, then there is no real novelty value to getting her attention. Please don't take this personally as I'm sure children don't realise how hurtful this can feel (I feel it too sometimes, though I try to ignore it). I also don't have family nearby and it is very, very hard sometimes, so I do sympathise with you.
Hope you can talk to your OH and make some sort of plan to tackle this. Only other thing I can suggest is if the local children's centre offers any sort of help that would be relevant - ours does a parenting course that tackles discipline among other things, and it also has a dad's group where the Dads can do fun activities with the children once a month (and leave mum free to do her own thing...).
Good luck! Sorry for the long post - trying to take my mind off my own problems at the moment!!!