Looking at the age and setup I think It might be the academy plastic bodied SA-80.
It's a pretty rare gun, but I don't think it's collectable, since more realistic metal bodied SA-80's have been about for just about as long as that one. If it is the plastic bodied version they were sold as budget guns back in the day. Roughly half the price of the Star/Ares metal bodied version.
Realistically I don't think it's worth a lot, Some collectors might want one for the novelty value, but new SA80's start at about £160ish and that is with a fully metal body and standardised gearbox.... This might not be a standard gearbox due to the age.
You don't need a licence to own or sell it.
You do need to ensure the person you sell it to has valid defence. Ukara membership is the easiest way to tell, A typical airsoft player will have a code and you can just phone any airsoft shop to check the code is real. Firesupport are very good for this.
https://www.fire-support.co.uk/
I don't think I could price it for you... It'll be sold untested, It's not a current make, and it's of a construction type that is not common. So realistically it's a wall hanger to a collector. So £50-80 would be my guess but I could be very very far off the mark with that.
