You can use the link below to search for day centres which can give some immediate advice.
You can use it look for accommodation for homeless people but this may need to be paid for. Your dad would be able to claim housing benefit for this or the housing costs of Universal credit if he is a UC area.
www.homeless.org.uk/
He should also approach the council to make a homeless application.
They will look at 3 things in the first instance.
1)If they have a reason to believe he is homeless (sleeping in car)
2)If he is eligible for assistance (UK citizen)
3)If he has a priority need. If has no automatic priority need they will look at his vulnerabilities.
Some of the groups that are classed as vulnerabilities are
1)those who are 60+
2)those who have an illness or disability.
The council only have to have a reason to believe that he he is vulnerable- they do not have to be satisfied. (basically means he does not have to have a lot of proof for them to consider him vulnerable)
The vulnerability test is quite subjective though.
The council would consider whether his age, illness or disability would make him more vulnerable than the next person if he is living on the streets.
If he is insulin dependent he can argue that he needs to keep his insulin in the fridge for example.
If he "passes" these 3 hurdles then the council will a duty under s188 of the housing act 1996 to place him in emergency housing whilst they consider 2 further hurdles.
These are
4)Intentionality- has he done or not done something to cause his homelesssness? (Please note that arrears do not not necessarily mean he has made him self homeless if he has a good reason as to how they occurred (lost job, relationship breakdown etc) The council must investigate this before declaring that £its his own fault)
- local connection- has he lived in area for 6/12 months or 3 out of 5 years- does he have family or treatment in the area etc.
The council must then give him a decision letter s(184) advising on whether they have a main duty to house him or not (should be within 33 days)
If they owe him the main duty then they can house him in either suitable social housing or a private rented house that is available for at least 12 months.
However since 3rd April this year the council have new statutory duties under the Housing reduction Act 2017.
If they have reason to believe that he is homeless and eligible but NOT priority need then they still have a duty to relieve his homelessness - this will entail the council completing a personal housing plan with him and helping him secure accommodation that is available to occupy for at least six months. (note that this does not mean they have a duty to house- only help him find accommodation. This duty lasts for 56 days although this can be extended.
Some councils have a homeless prevention fund and can help with upfront costs or pay the deposit.
If the council refuses to assist him at all - this would be unlawful and it can be challenged with the help of a Civil legal advice caseworker. He should be entitled to legal aid for this if he is on a low income.
www.gov.uk/legal-aid/eligibility
I appreciate this is a lot of information but if you are aware of your dads rights it can be easier to deal with the council and will hopefully stop them telling him "they can't help"
england.shelter.org.uk/housing_advice/homelessness/guide/homeless_get_help_from_the_council/how_the_council_can_help