The net amount of tax that you will pay between you will be the same either way, so it is personal preference really.
Option 1 : You opt for joint assessment, and transfer your personal tax credits to your husband, he will get more take home pay than usual, and you will get less during the year, but the net tax that you pay between you should be less. You will still have unused tax credits when you go on unpaid leave. Your employer may refund you these tax credits over the course of the year, some do, not sure if this is the norm, you should ask payroll in your company,
Option 2 : You opt for joint assessment and leave your tax credits as they are.
You will both get the same take home and you will have unused tax credits at the end of the year, and you can apply for a tax refund.
You should opt for join assessment either way, as you can then take advantage of maximizing the use of the tax bands between you.
I would recommend that you use
www.taxcalc.eu to try out the different scenarios