I guess this question should say if once can depart legally. While it is always a good idea to look at as much available information as possible.

I found the following which suggest one cannot legally depart from X for Y without consulting the area forecast.

ENR 1.10 - 1
1.1 Before beginning a flight, a pilot in command must study all available information appropriate to the intended operation and,in the cases of flights away from the vicinity of an aerodrome, flights over water (see ENR 1.1 Section 11.11) and all IFR flights, must make a careful study of:
a. current weather reports and forecasts for the route to be flownand the aerodromes to be used;

1.2.1 Forecast information must include:
a. an aerodrome forecast for the:
(i) destination; and
(ii) when required, alternate aerodrome; and
b. one of the following:
(i) a flight forecast; or
(ii) a GAF (at and below A100); or
(iii) a SIGWX forecast (above A100);
and
c. a wind and temperature forecast

In section 1.2.2 (below) a mention is made of flights which require a forecast. I haven’t been able to find a section which clearly distinguishes between flights which require a forecast and those who don’t.

1.2.2 For flights for which a forecast is required and cannot be obtained, the flight is permitted to depart provided the pilot is satisfied that the weather at the departure point will permit the safe return of the flight within one hour of departure. The flight is permitted to continue provided a suitable forecast is obtained for the intended destination within 30 minutes after departure

My question to the community is where can I find the definition of a flight which requires a forecast. I was hoping the AIP would make this clear, but reading the sections did not help me. It refers to "must study all available information appropriate" but then goes on to say that for flights over water and IFR the listed items including the forecast must the studied as well.

Any feedback is much appreciated.
PS: I am aware one should always get a forecast, but I am after the place where it defines the legal aspects rather than good airmanship.

It has been some time since I last thought about this question; please treat my response with some caution.

My question to the community is where can I find the definition of a flight which requires a forecast.

The answer lies in AIP ENR 1.10-1 that you cited at the very beginning of your post.

You will need a forecast for:
1) Flights away from the vicinity of an aerodrome - this used to mean more than 50nm
2) Flights over water
3) IFR flights

In summary, a forecast is not needed for a local VFR flight in the vicinity of the aerodrome - ie within 50nm. This does not absolve the pilot from making a visual assessment of the local weather prior to flight.

Common sense and airmanship would dictate getting a forecast if the weather is marginal and you plan to leave the circuit area for a VFR flight within 50nm.