To secure Britain has a place in space activities that are private as well as ones run by UKSA and ESA. To Bring in more money to the economy and create new jobs, with a small (possibly non existent) cost to the public.
Change space policy to make it easier for companies such as Virgin Galactic to set up in the UK where they can launch their space vehicles from the UK.
Virgin Galactic has already shown interest in setting up their EU launch facility in the UK, but might not be able to due to how things are currently done in the UK.
Changing this could create new jobs and bring a lot of money into the economy.