Your watch looks lovely.
The dial is in great condition which is a plus. Ditto the case, winder and box. Given the age of your watch, I suspect parts shouldn’t be a problem since Tissot and Omega were linked back then. I can’t discern the movement number but I expect there’s an Omega equivalent.
So, for value, I suggest you look on eBay at the completed/sold listings and add a percentage to the price given your condition and assuming it is serviced although the value may not recoup the cost of the service.
In the UK, I’d expect to pay about £120 plus parts and postage for a service.