Hello, without being too much of a pain, I thought I'd brought water effect, it arrived today, and basically its bright blue and thick, nothing like I expected, I know a lot of people use something called gell, and again due to my limited knowledge on this subject, I want something I can buy in the U.K - to cut a seemingly long story short, this is what I am after for a diorama based on a 1-72 rescue boat tied to a dock, the sea to be almost transparent, so something I can pore on and self-level. Can anyone help me ? Look forward to your reply.

There are tons of ways and different products. I can't quote products for you because I do remember they are different in England vs. the US.
Check out this area at the top are two features that shed some light on water.
MSW Features

A lot of ship modellers use Acrylic Gel Medium (available from art supply shops here in the UK) although, typically, this is used for water 'out at sea'.

For still water, I've had some success using Tamiya X22 gloss applied a drop at a time with a syringe albeit this was in 1/350th scale so I don't know if the effect would scale up to 1/72, you can see the effect in this pic:



John