Back to work terrifies me

Well this morning I have been out to buy a suit.  After leaving my career behind to care for the kids full time, something has come up that interests me greatly.  I am a software developer and team leader by trade, having worked on some rather large projects for multinationals and government organisations.  This is the kid of job you can't really go back to part time so when this opportunity cropped up I was initially a little sceptical as to how much it was worth to be to be back in work.

In the end, the amount of money I will get different to now is not massively different, yes it's more, but mainly I will be feeling better about not scrounging off the state (I haven't been out of work since I left university - in fact I haven't been out of work since I was about 17).

I have a couple of concerns - I spoke about consistency previously and I am worried how, if I go back, the routine for the kids will change and how that will affect them.  I am also concerned that having a couple of years off in the IT industry is worse than other industries where the technology and the required skillsets don't progress as quickly.  Can I still pump out the same quality of software I always used to? Probably not for a few months while I get back to grips with things, but I have had to learn from scratch before and have the drive to do so again.

Next problem I face is one that will be quite familiar to pretty much anyone coming off benefits I would have thought, but having not been in this position before I find it quite daunting.  Benefits gives the family enough to exist, I have done my best to save a little but most of those savings were used just before Christmas when I had £700 of repairs needed on my car.  Will we be able to stretch the amount I have saved to last the first month of work until I get paid, or can I time it well enough to make sure I don't have to do something like that?  Hopefully things will line up well enough.

I should re-iterate that I haven't been offered a job yet, just an opportunity that I am looking into.