Based on the information provided the CAA would not deem your operation as commercial, as I do not believe your type of operation falls under the definition below:
‘any flight by a small unmanned aircraft except a flight for public transport, or any operation of any other aircraft except an operation for public transport;
which is available to the public;
which, when not made available to the public,
in the case of a flight by a small unmanned aircraft, is performed under a contract between the SUA operator and a customer, where the latter has no control over the remote pilot
in any other case, is performed under a contract between an operator and a customer, where the latter has no control over the operator,
in return for remuneration or other valuable consideration.’
The key elements in understanding this term are ‘…any flight by a small unmanned aircraft…in return for remuneration or other valuable consideration’.
The term ‘available to the public’ should be interpreted as being a service or commodity that any member of the public can make use of, or actively choose to use, (e.g. because it has been advertised or offered to someone).
‘Commercial operations’ allows a broad variety of flight applications, predominantly centring on aerial photography or the operation of sensors and other data-gathering devices. The essential question that needs to be asked is “what is the purpose of the (specific) flight?” i.e.“If I were not receiving payment/valuable consideration for making the flight, would it still take place?”
In terms of insurance the CAA only enforce that insurance is in place for commercial operators, therefore it is down to the individual recreational pilot where they deem insurance needs to be in place.
To complete the flight the pilot must abide by the drone code and Air Navigation Order which states you must not operate within 150m of a congested area. The definition of a congested area is:
‘ Congested Area’ in relation to a city, town or settlement, means any area which is substantially used for residential, industrial, commercial or recreational purposes’
I can confirm golf clubs can be regarded as congested areas as they are available to members of the public. If however the owner of the club is able to cordon off an area of the golf club, so that no other individuals not under your control are within the area, then the flight may take place.