If you intend to track your car 2-3 times a year then yes you will get your fee for join back on first occasion. PCGB pricing is competitive compared to the big TD organiser
FWIW and IMHO at Oulton, as far as spectating goes, as a point of order/etiquette, leaving the row or two immediately behind the pit garages for the participating cars makes life a lot safer and simpler.
I'll be there spectating in my Focus ST Edition so come say hello. Hope the track clears quickly after the storm due from 3pm today until 8am tomorrow.