DFC said:
Supersport,
Your Scenario and your question do not match.
Your Scenario is that you are departing on a VFR flight to Barton and have ensured that is a safe course of action. During the flight, you may change the plan and route to Blackpool if the weather changes but by your own admission you do not expect that.
Thus your destination at the time of departure is Barton and that will only change if there is some unexpected change in the weather.
If you are the type of pilot that always plans a suitable altenate for your intended destination then will you have a suitable alternate for Barton?
Nothing illegal with departing for Barton at all provided that in your aircraft the 4 hours of fuel is suficient to fly the proposed route plus contingency and arive at Barton with sufficient reserve fuel.
Thanks for the lengthy reply DFC, a simple
"No, it's not illegal" would have done just fine.