Health insurance as an employee benefit

Assalaamualaikum,

My employer offers health insurance as a benefit for employees via AXA. This is an optional benefit meaning you can either opt in or out.

I do not directly pay for it and the contract is with my employer. However, because it is a benefit it’s taxable, so there would be a small amount I would pay through tax.

There is also a £100 fee that you have to pay for the first claim every year.

Through the plan I also get a 40% off a gym membership.

Would this be a plan that is permissible for me to join? If no, can I join for the purpose of enjoying the gym benefit only?

Jazakallahu Khayran