very leggy squashes

[Florence Fennel]

..on the windowsill, I hasten to add!
BW
Flo

[Two_Sheds]

By the way they are in 25" pots- so quite large but wanted to make sure they were big enough

that's a recipe for disaster really.
The unused compost will go sour and could kill your seedlings. You need to sow into a small (3") pot, then pot on as the plant gets bigger - gradually, into slightly larger pots each time.

[Mchanen]

Well i have got rid of my lanky courgette plants and sowed some more seeds (into smaller pots) so hopefully they will turn out better this time.