katiekoo12002,
You are protected by Law. You will normally have to stop flying as soon as you know you are pregnant. Your employer must continue to pay you but can expect you to take alternative work within the company (eg. Ops, Crewing). You will qualify for Materninty pay, this is for 26 weeks. For full details look at the Department of Works & Pensions website.
http://www.dwp.gov.uk/lifeevent/bene...ernity_pay.asp
p.s Ignore Workinghards post. You've paid Tax and national insurance for a reason. He is correct the tax payer is paying and that is you. I imagine if he is run over by a bus he will have no problem in accepting an offer of help from the Ambulance service and NHS.