"Cost of antenatal services"

I am Australian but married to an English man local to the northampton area, we moved from Australia to England in July this year when I was around 12 weeks pregnant. We also have a 2 year old son. Due to bad advice given by the official government departments regarding visa I did not apply for my spouse visa before I came and instead came on a visitor visa with plans to apply for my spouse visa when we were settled and my husband working. We have since been let know that this isn't possible that I would have to return to Australia to apply and it would take 12 weeks to process so this not being an option I instead only have the option to extend my visitor visa which would allow me to work but no access to NHS I can't even register at my husbands family gp, nor can our son until I pay and have him declared a dual citizen. So I'm left with no choice but to go to the only gp in the area who would accept my registration, a clinic that caters to homeless, refugees and drug addicts. Don't get me wrong the staff are lovely and I have been well looked after and my care which is a shared plan with the northampton general hospital until today had no complaint, but to receive an invoice today for over £3000 to say I was shocked, is an understatement! ! For everyone out there who think us forreigners are robbing the NHS, I assure you for some of us it's the other way around. in Australia private care would cost this much!