Hi Kingsburysteve.

Welcome to the forum. 

It's not too late to claim, but simply having cancer (or have had cancer in the past) isn't sufficient.  It is only paid if you meet some very strict criteria on the day you make the application.  In essence, there must be some serious impairment to your daily living or getting about.  In practice, you'll only get it if you have some obvious (and preferably visible) disability, such as a leg missing, or you're blind.  The process of applying is aduous and difficult, you'll be called in for an assessment, and they tend to turn down most applicants.

The experience of my wife and many others is that it is a unsympathetic system designed not to help people, and when you do apply they treat you like a lying piece of ----.  

If this hasn't put you off, then before you apply, I suggest you find a local disability support charity and ask them for help.  The form is massive and it really needs to be filled in by someone with experience.  There is also a strict time scale for returning the form, so it's best not to ask for it until you've got all your ducks in a row.  Again, this is why you really need support to fill it in.

My advice is that you should expect to be disappointed.  If you don't need the money, don't bother applying.