The Harbourfront would be a great venue for a small wedding party but I would imagine that 30 people would be about the maximum they could accommodate.
They have also just opened a new Bistro/Bar in Trearddur bay called the Black Seal, which is right on the Beachfront and a lot bigger. If they maintain the quality of food etc. this might be an alternative to consider.
As above... contact them by phone or Twitter. They are very friendly and I would imagine that as long as the cost of the wedding covers what they would normally take on the day in question,they might do it.
Suggest you give them a call -- they have a website which has their telephone number.
The best way to contact them is via their Twitter page.
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