Thanks for your replies guys, very helpful. I hadn't thought of fitting it within expandable foam, I can see that that would work as I have used the stuff before and it does hold pretty well.
Tickly T, I was thinking exactly the same as you; a noggin with the three holes drilled out, then split lengthwise, using screws to clamp each half securely around the manifold.
However, after some more thought and a trip to my local engineering supplies shop (with a couple of bloody clever guys behind the counter who have a solution for everything!) I have just completed the installation by buying a length of stainless steel stud to make 2 'U' bolts (the guy in the shop said this would be better than over the counter U bolts as you may nog get the 'U' size close enough and the thread deep enough), with 4 largish washers and stainless nuts. The stud bent reasonably easily enough around a hammer shaft which was clamped to the workbench. Ends then cut off leaving a suitable amount to reach through a length of timber noggin. This was secured immediately above the manifold and then the clamps tightened around the manifold and through the noggin. It has worked a treat and the tap is very secure, level and the outlets protrude squarely.
Regarding the threads TicklyT, you were right....I wish I had read your reply this morning before my 3 trips to the plumbers merchant as I couldn't get a seal!!!!!! In the end I used 15mm x 1/2" compression couplers and flexi tap hoses, with plenty of PTFE as I had some washers, but the thread of the coupler wouldn't reach all the way to the back of the threaded olive supplied with the manifold.....
It has taken me all day (I am just a DIYer and not a trained plumber), but with a list price of £350 and supposedly a product for the UK market it is a joke. The manifold is also too deep for standard UK walls. It is lucky that I am fitting 20mm Wedi walling and then 12mm stone tiles or else the manifold would be sticking through my finished wall....unless of course I re-battened the whole wall to make the void bigger...........
How do you professionals deal with all these pain in the @rse problems on an everyday basis! I would be surprised if you could make any money out of a job like this with all the extra hassle and improvising which all takes time! I'll stick to flying planes, much easier!!!!!
Thanks once again. I was going to insert a picture of it, but I can't work out how to do that either!