Very good question…benefits are so complicated and, frankly, messy that it’s amazing that anyone manages to find their way through the maze and get what they’re entitled to.
One thing I suggest you do is use one of the benefit calculators online. Turn2Us.org.uk has a really good one as does entitltedto.co.uk.
Also, there is a list (though not all in one place) of all the benefits there are on the government site Gov.uk. The information is across lots of sections on the site but if you put ‘benefits’ in the search bar you will find a lot.
Of course here at MoneyMagpie.com we try to keep on top of the latest benefits, so do look at our Benefits and Debt Assistance section here https://www.moneymagpie.com/manage_your_money_categories/benefits-and-debt-assistance
Finally do speak to one of the debt advice charities like StepChange, Community Money Advice, Christians Against Poverty or Citizen’s Advice as their advisors are really good on benefits and what you could claim.