Although E111 is often pitched against travel insurance in an either/or way, this is really not the way we should be thinking about these two forms of cover. Both E111 and travel insurance do different things, and having them both gives you the best cover you could have when travelling to one of the 32 countries which are part of the E111 system.
E111 is purely a healthcare cover system, and allows British people travelling overseas to use the state healthcare in any of the other E111 countries. Using E111 means you’ll get your healthcare free, or at the minimal price which locals pay for the same service. Of course you could choose to claim for healthcare costs on your travel insurance policy, and if you choose to go to a private hospital that’s your only option. Travel insurance policies have excesses though, and paying the excess could end up much more than claiming on your E111.
There are other services which travel insurance offers though which E111 never covers. Travel insurance will pick up the cost of flying you home to a UK hospital to continue your treatment, whereas E111 will only meet the costs of local treatment and not repatriation. Depending on the policy, your travel insurance might also pay for private care and extras such as physiotherapy. Don’t forget that travel insurance covers a lot more than just medical emergencies on your holiday. A good travel insurance policy will also pay out if you experience flight delays, have valuables stolen or have additional costs to replace a lost passport. Not all travel insurance policies are the same, and if you’re planning on doing something like skiing or scuba diving, you should check carefully to make sure you have adequate cover. Many travel insurance providers will give a discount for policyholders who also have E111 cover.