I have just had a reply from Solux it seems they ship to Singapore directly from their warehouse in Taiwan.
In fact it would probably be cheaper for me to buy from there and ship to the UK.
These are the people involved:
www.eiko-ltd.com
If you want a price you can email: Aaron Liao at
aaron@eiko-pacific.com
and give him your requirements for, "color temperature & beam spread" and he'll give you a price.
[Don't forget you will be projecting the light from air to water so the high refractive index of water will reduce the beam spread by quite a lot so get the widest beam angle possible. ]