Your guarantor doesn't need to be a homeowner, but if they are, we may be more likely to be able to accept them, so we always recommend asking someone who owns their own home first if you can. Don't worry, their home isn't at risk.
A suitable guarantor is someone who is aged 19-75, has a good credit history and hasn't had trouble paying their bills in the past, and who can afford to make the monthly payments if you don't.