I know nothing about the NHS scheme, but as @MFillingham says you will save 20% tax (assuming you are a basic rate taxpayer) plus NI, so the £290 is actually costing you less than £230 a month. You will gain £330 every 4 weeks in PIP by not having a Motability car, so you have over £100 a month towards any other costs above the leasing cost (plus of course any AP that you would save), so it looks like it’s well worth investigating.