I doubt that more than 50% of Westminster MPs have a Welfare Advisor (WA) on staff - many don't even have a physical office in their Constituency.
It's a weird situation - a few MPs started employing WAs, legitimately paid for from Parliamentary expenses, in the early 80s as unemployment shot up and benefit reforms turned the system ever more Byzantine. The practice spread over the following decade or so; I don't know what the position is now but WAs in Constituency offices, or alternatively contracted out to the Voluntary sector but paid from Parliamentary expenses, was in the past very strongly limited by political affiliation of the MP. Arguably adequate WA services should be funded by Local Councils and be completely separate from any elected official, the provision by MPs is a way to use Parliamentary funds to make up for the lack of funding elsewhere, a sticking plaster rather than a cure.
Westminster MPs are under no obligation to do anything, to provide services or support constituents. Their status - unless on the Government payroll - is still that of the Private Member of the pre 20thC era when they were unpaid and took the role solely for position and advantage - it's just that now they are paid and their contribution to society is dependent on either a moral/philosophical commitment or the need to appeal to voters - the latter doesn't impact where the local demographic is single party focused and votes go to a Party irrespective of the behaviour of the candidate while in office. Bottom line - don't rely on your MP having a WA on staff, or offering any support for Benefit or Health related issues.
