I came off income support in January and went back to work 20 hours a week. I'm a lone parent to two primary schoolers.
With working tax credit and the 'childcare element of working tax credit' (CEWTC) along with my part time wages of only £130 a week, my income is currently around £1300 a month.
I'm not currently entitled to housing benefit or council tax benefit as I have savings, but if I was I would even more financially stable, and hundreds of pounds better off a month than being on lone parent non-working benefits.
Of course, depending which part of the country you're in this income might not stretch so far. I'm Northamptonshire, small market town.
As for childcare costs, my two have to go into a playscheme every school holiday as I don't have anyone else to help, but CEWTC covers most of that.
However
bear in mind they pay that cost weekly spread over the year, so you do have to find a lump sum every school holiday to pay your childcare provider.
For instance, I started work January and the first school holiday was February half term, so I had to find £140 I think it was to pay for the playscheme. Luckily I had savings, but I'm presuming other people will save up for childcare costs, or use credit. Over the year it all works out, but on a weekly basis, you have to remember to keep money by for the lump sum costs of childcare.
I'm working in the worst line of work in the world but these sorts of companies always offer very flexible hours including ones that fit in with school times which is why I took it, also it's a CV gap filler until I find something more sane and fulfilling.
I have to say though, with the tax credits, I'm better off part time than full time. If you're a professional though, of course your full time salary will make you better off than part time. I'm just an average person who's only ever worked in admin, call centres and shops. Well, apart from the flower picking, art studio and motorbike courier but them's a whole other story of my life 
Summarily, when returning to work after income support, drop all the overthinking and worst case scenarios as I learnt, and just jump in blind, there's no other way. Trying to research the better off calculations and practical logistics will just drive you potty in the end. If it's doable on a part time wage like me, you'll manage.
Full time wage, I have no experience of (as a lone parent), hopefully somebody else can advise.