THanks folks. However, BA comes up an error and Catay wants me to log in with my MP account. I don't have one. I have a BAEC.
ISo in a nutchell I cant book a revenue seat and reduce with Avios. That is fine. I'll get a PE seat and then do a TP run to HQ. :-) GLA-LGW in club and do my usual 5k avios to reduce the price :-)