To be fair if it’s Just class one business has to doesn’t add anything to most premiums - going to more than one location be it full time job with two locations or a full time job and a part time job you should have business use.
It’s if you have class 2 or 3 it can get expensive - class 3 is selling
Found this on the bewiser.co.uk website
Business Class 1/ Class A
This class is the most common and will normally permit the policyholder (and/or spouse) to use the car for travel between multiple fixed places of work in addition to use for social domestic and pleasure use. Common occupations that might require such class of use would include a supply teacher, a care worker who drives to see various patients, or any person who might have to work at more than one location. Any named drivers other than the spouse will not normally be permitted to use the vehicle for business related mileage, and any commercial use relating to delivering goods or selling products will not be covered under this class of use. The cover provided is essentially for travel between multiple places of work but excluding use of the vehicle as a tool of trade.
Business Class 2/ Class B1
This class normally extends the cover under Class 1 (above) to any named drivers on the policy. Most insurance companies will require both the policyholder and the named driver to use the car for the same business (i.e. the insured and the named driver cannot use the vehicle in connection with different businesses) The same restrictions found in Class 1 still apply in relation to the usage; so again, any commercial use relating to delivering goods or selling products will not be covered under this class of use.
Business Class 3/Class B2
The final business class is the broadest in its cover. In addition to the level of cover provided under a Class 2 policy, the policyholder will be allowed to use the car for ‘commercial travelling’ purposes as well. This class ensures that any employment related car travel, to an unlimited number of destinations that are not fixed, will be covered. This would therefore be the relevant class of use for those who use their vehicle as a tool of trade, such as sales representatives visiting customers. Persons requiring this business class of use are likely to be high-mileage drivers and this is, as you would expect, normally the most expensive annual premium cost.
Note that this Class 3 use, although the widest of the Classes of Use, will still exclude certain uses regarded as non-standard; such as use as a taxi (public and private hire use) or use in connection with the motor trade. For these uses it will be necessary to purchase a commercial policy.