You probably have this one, (12.13", model #07790)
http://www.telescope.com/Accessories...s?ensembleId=4
but need this one, (11.63", model #07715)
http://www.telescope.com/Accessories...s?ensembleId=4
See below on above links for full listing.
Bintel have both listed side by side and the 7715 is described as being for 10" SCT. Looks like Skywatcher has slightly smaller OTA than other 10" Newt which are typically around 12" OTA.
https://www.bintel.com.au/product-ca...ilters/page/2/
You will still have to tighten the three nylon screws for best fit and/or add a bit of Velcro (the loop side only not the hooks to the OTA) to give a more snug fit. Note still use the three screws as the filter may work its way off if relying on a snug fit only. Or put an elastic band between the safety screws and secondary spider screws. I have a three vane spider so it lines up. Make sure you cover your finder on the front lens side to prevent heat entering your finder and on the eyepiece end to avoid temptation to look.
Always double check filter is in position and all possible openings outside the OTA are covered (essential for 'scopes without a solid tube). Line the Sun up using the smallest possible shadow on the ground behind the OTA and use a low power eyepiece at first.
Safety first and always is paramount when observing the Sun!