My wife is off work due to illness and recieves the weekly state benefit only. I'm wondering, is it possible for her/us to claim Mortgage Intesest Supplement benefit given that I am in full time employment?
If you work more than 30 hours per week, then you will not be eligible for Mortgage Interest Supplement even though your wife is currently on SW payment.
It depends. If the amount being paid is very high, it may be paid for a limited time to allow the homeowner to make alternative arrangements (rent a room, sell, re-negotiate, etc). A limited duration payment would usually be made clear to the customer at the start of the claim.
What constitutes "very high" is a bit of a grey area, but it may be related to rents and rent limits in the locality.
For general cases, payment of the supplement is open-ended as long as there is an entitlement.