Hastings Arts Forum is the most obvious port of call - no.36 Marina in St Leonard's, it's worth walking in there and enquiring. Better would be to post an item on their website, there are often people renting out spaces or looking for studios. You need to be a member to post stuff - but I would be quite happy to post an item on your behalf (half my friends are artists).
Let me know if you want to post something in the members' area of the website. You will need to give details of whether temporary or long-term, for yourself only or willing to share a studio/workshop? Painting/pottery/whatever? And a contact number/email address!
You won't be able to Private Message me yet if you are a newcomer, but you can email me:
jazzloony@aol.co.uk.
Also, there are several studios/workshops along the Marina in St Leonard's. Very friendly people and it's worth walking in and enquiring.
Good luck.