Like you, on mine I took the nearside head off first as it is the slightly easier head to get off. It was the gasket on this side that had gone.
As I had bought a full gasket set with both head gaskets and head bolts, I decided to remove the offside head as well and was glad I did.
Although, the gasket hadn't gone it was in poor condition and I don't think it would have lasted much longer, so for the extra work involved, it was definitely worth it, rather than having to strip the engine down again in the future.
I also redid the oil cooler gasket, while it was apart as there was some blue antifreeze colour on the nearside head, replaced the thermostat, water pump, auxiliary belt and a new cambelt kit.
When I removed the oil cooler I could see the gasket had been leaking, I also had an overheating problem in traffic, which is why I replaced the thermostat, and although the water pump had only done 65k, there was a whistling sound when I revved the engine, the new water pump and auxiliary belt has cured this.
I hope this is of help