Thanks for all the replies. In answer to some of them……
Druidh, I may well take you up on the offer though, as you say, I think size would be the problem.
The idea of buying a frame and getting everything built round it is very appealing, but I was under the impression most manufacturers only sell their top end frames as frame only. Also, when I’ve done rough pricing and compared it to off-the-peg bikes it works out quite pricy. Canyon, for example, sell bikes that are so well specced and at such prices you wonder if it’s legal!!
I agree re fit and will probably use the Tri Centre in Edinburgh whom I’m told have a great fitting service. I do get lower back problems on longer rides, though am looking into pilates or yoga to try and help that.
Mark, would that be a Cube by any chance?
The other recommendations I will definitely all have a look at. Cheers.