George Osborne may be slashing the benefits budget to save cash, but part of the problem with our welfare system is the amount that goes unclaimed each year. In 2008/09 £12.7bn of means-tested benefits and £5bn of tax credits went unclaimed, a far cry from Osborne's view of people taking unwarranted benefits as a "lifestyle choice".

I'm not surprised. Even universal benefits which have a much higher take-up rate than means-tested benefits can be hard to claim. The health in pregnancy grant was introduced in 2009 as a one-off grant of £190 to each pregnant woman. Though it is being scrapped by the government, women who are 25 weeks pregnant by 1 January 2011 are entitled to claim it. Yet I almost fell at the first hurdle last week when I tried to make my own claim. My midwife had told me that UCH, one of London's major hospitals, had run out of forms, and as she did not know when or if more would be coming, she suggested that I try my GP, who categorically told me that the benefit and therefore the claim form did not exist.

Being bolshy, confident enough, and with a good enough command of English I insisted that it definitely did exist, and did what often seems to be the only way to get what you need – I made a fuss. I insisted she ask colleagues. I refused to sit down in the reception area and instead stood over the receptionists while they searched the cupboards. I showed them the relevant page on www.direct.gov.uk. Eventually a form was found, filled in and sent off.

There are many reasons why people do not claim benefits to which they are entitled. According to the charity Age UK these can include being put off by the form filling involved' thinking of benefits as something for "other people"; having applied in the past under different circumstances and been turned down and even fear that the government would pay them too much and then ask for it back as per recent media stories. But, they say, the biggest reason is that people don't know about the benefits. "Someone might own a house and think therefore that they're not entitled to any benefits but, for example, pension credit or council tax benefit ignores the value of your home," a spokesperson told me.

To counter this, Citizens Advice launched a campaign earlier this year calling on government to set higher targets for the take-up of welfare payments. They get over two million inquiries about benefits annually, and their research showed that up to half a million households entitled to housing benefit do not claim it, that up to 3 million households are missing out on council tax benefit and as many as 1.7 million pensioners are missing out on pension credit they could be claiming.

Of course doctors and other frontline staff can't know everything about every benefit, even the ones claimed via forms they must sign. After all, The Child Poverty Action Group publishes the Welfare Benefits and Tax Credits Handbook each year, and the 2010-11 edition runs to nearly 1,500 pages.

But had I not been such a pain when I saw my GP, I would never have got my form. And though in theory I could have called a helpline to send a form to my doctor for me, this would have depended on me knowing about the grant and my eligibility for it, and my not believing the doctor who denied the existence of the benefit.

I wonder though how many people in my deprived part of London – where over 190 languages are spoken – would have just accepted her first answer and would have missed out as a result, deferential to a GP telling them something wasn't possible. And while such an approach may save the government money in the short term, it will prove to be a false economy, increasing poverty at times when people most need help.