I have 8 steel bikes, including 2 steel touring bikes, and 1 titanium bike made by Lynskey, it was their lowest end model in 2013 called the Peloton. That Lynskey bike is by far the most comfortable riding bike of all my bikes...except for the touring bikes, but they're riding on fatter tires with less psi. All my steel road bikes and the Ti bike ride on 23c tires on the front and 25 on the rear, and the ride quality of the TI bike is noticeably smoother riding.
If you can swing getting a TI bike, without going into debt to do so, then, by all means, get one. I don't think getting a more expensive TI bike will give you much more than a lower price one, so save some money and get a lower priced bike. My Peloton came with 105, but I did make some changes before I took delivery and had an Ultegra rear derailleur put on, all I had to pay was the price difference between the 105 and the Ultegra, the other changes I made was not going with the Lynskey fork since they couldn't tell me where it was made, and swapped it for a Enve 2.0; also removed the cheap FSA headset and had a Cane Creek 110 headset put on instead; those were the only changes I made. The 105 components have held up very well, as has the Ultegra, I'm not racing so I don't see any need for Dura Ace or full Ultegra.
In the UK area you may want to check out Planet X, but Planet X is out of stock you would have to call them to see when they expect to get them back in stock, but they have been raved about yet don't cost much. Another option is Unicorn, goofy name but they do make very affordable TI bikes.
Now I showed you a couple of inexpensive TI bikes, others have shown you more expensive ones, you have to figure out, or maybe you already know but haven't told us, how much money you want to spend without going into debt for it, then figure out if you would even feel a difference between a $1,900 bike vs a $8,500 bike, the answer is probably not, so is spending more money for a bike worth it? Only you can answer that question.
