Dave,
Yes, all true. They even rebuilt F4 airframes into Avon 200-powered variants - a major rebuild which included taking out the centre fuselage tanks and fitting the rear fuselage ones, as well as lots of other changes.
The RAF service of the FR10 ended about the end of 1971; indeed, after that the only "operational" RAF squadrons were 45 & 58. (Quotes because they were really an extension of TWU - I don't think they had allocated war roles). So I am puzzled as to why Brawdy was interested in an F95 fit some years later.