Thanks for the advice.
I've only just realised that Red Rum is, in fact, just branded fork oil. I've done a full service a few months ago, so I've got plenty of fork oil anyhow.
CRC seem to be out of fork grease at the moment, so I'm just going to try to get the new seals in without greasing the recess in the lower leg.
Should be fine now - I didn't replace the seals when I did the service, and have just noticed the fork is leaving really gunky crud on the stanchion again, it is also feeling a tad notchy - probably meaning the oil I added has been depleted by the poor seal.
The dry weather means the fork is getting an absolute hammering at the moment!