IIRC the family emigrated to Australia for one series or film - possibly a tie-up with an Australian TV company. Probably had a "Whingeing Poms" slant.
Only remember the episode documenting their eventual return to England after supposedly being away for several years. Alf goes into his local pub and his old mates greet him with remark something like "Been away on holiday? Have a nice time?". Which just about sums up the returning ex-pats' usual reception.