Aeropars:
Impossible for somebody else to answer for you but these are some factors to influence the decision.
1. How long can you manage without heat? Could you use electric heaters to keep warm?
2. Does the boiler also do hot water. How long could you manage without hot water?
3. How old is your boiler? These policies don't replace old boilers. You need to check the small print.
4. Is you boiler a lemon? These companies won't renew cover on a lemon.
5. All boilers should be "serviced" annually (sometimes just a safetry check).
6. Most boilers only breakdown infrequently.
7. Some boilers break down frequently.
8. Some spare parts are VERY expensive.
9. Is someone at home all day to admit the repair person when he/she calls at a time of his/her choosing and then goes away for spares only to return another day.
If its a major brand boiler and you are risk averse then consider a maintenance contract with the boiler company's scheme, not a utility where you have no control of the service engineer's experience and spares holding with your particular boiler.
The electric cover I reckon is a total waste of money.