can someone give me some advice on getting the seal back
into the fork while its on the inner tube.
I dont want to damage the seal so just cheacking if there is an
easy way to do it.

CRM'er

I dont know if this a stupid question but how have you managed to get the seal out of the slider without removing the fork leg from the slider?

Best way is to undo the retaining bolt for the fork leg, take it out, put the seal into place and put the fork leg back in - i cant see any other way of getting the seal back into place unless you have a nice bit of scaffold pole.