You're best off using the correct boot for the correct ground...
You'd struggle using full studs on astro but you could get away with using moulds or blades although your feet may 'burn' up a bit!!
That been said in the leagues I play in that play on Astro it is strictly no studs/moulds or blades...
Trainers are ok for a social but you'll struggle to hit the ball as hard and you would be more likely to roll an ankle or slip etc etc.
For grass I'm still using moulds at this time of year, you could prob get away with them all year round
You can get a pair of cheap astros for £12 from Sports direct... so just get a pair, will make you feel better anyway

My personal favs are Puma Kings but I'm old school!!!