Housing Benefit is not affected by your partner working full time but his income will reduce what you might receive and if enough, may prevent payment entirely. As a rough calculation, your HB will be reduced by 65p a week for every £1 of his income.
A loan is available to help with the interest on a mortgage, it is repayable on the sale of the property, you need to have been receiving your ESA(IR) for at least 39 weeks to qualify.