No, you shouldn't need to purchase health insurance as you will be covered by the NHS.
However, next year the UK government is planning to introduce a levy fee in order for visa holders to be able to access the NHS for 'free'. For students, it is expected that this levy will be £150 per year of the visa validity (£200 per year for other visas), which will be added to your visa fee when you apply.
As long as you will be studying at masters level or higher, your husband should be able to qualify to join you on a Tier 4 student dependent visa, which will give him the right to work in the UK (I'm assuming he will also have to pay an NHS levy).
If he cannot qualify for a dependent visa though, he will not be able to move with you unless he can secure a sponsored work visa. Unfortunately, work visas can be extremely difficult to qualify for unless he works in a very specialised, highly skilled or in demand field... because otherwise the company has to prove there is not a single person in the UK or EU who can do the job before they can sponsor him for a work visa... and there are very few jobs which no one out of the 500 million people in the EU is qualified to do.