C*nt on LY07UVR, a red and white motorbike

trackday is still classed as a closed circuit and therefore you still invalidate your insurance. why do you think they ask you what you will be using the bike for when you insure it.

I have an old Citroen AX back then (surprisingly reliable), and I loved driving it a lots that occasionally I enter track day occasionally just to have a blast (the car is extremely light despite having a weak engine), when I read the agreement form of the insurance company that I insured my car with; they specifically said that the insurance is valid for road only, not off-road, track racing etc. that'd either need a different insurance or a seperate insurance.

you're mucking about on track with a higher chance of a cock-up than on the road, that alone should be enough to realise that your current insurance for the road where you drive sensibly and carefully isn't good enough to be covered on track.