Hello,
I use Japanese saws. When starting out, the first decision was Japanese vs. western. It sounds like that is where you may be. It's a tough decision, because it costs money to make an adequate test.
To test a Japanese saw for dovetails, you could try the rip side of a small ryoba, 180mm to 210mm range. But a backed saw (dozuki) is better for most people.
Oddly, it is very difficult to find a rip-tooth dozuki in a changeable-blade saw. The least-expensive rip dozukis I know of are those sold by Lee Valley--one Korean-made in the $25-30 range IIRC, and one at about $80.
There are a couple of changeable-blade dozuki-type saws with composite toothing patterns that are close enough to rip to do the job. For example, an offering by Japan Woodworker, catalog #19.303.0, which is a Gyokucho, 19-point, backed, composite tooth saw advertised as a dovetail saw. I have this saw and it will do the job. $38.95 + shipping. I'm listing these as benchmarks--you can probably find the same saw closer to home. There used to be a Gyokucho 'Sunchild' which was OK also, but I don't see that one advertised anymore, at least in the US. You may be able to find it in the UK.
One type of Japanese 'dovetail' saw I would advise against--for the purpose of sawing dovetails--is the 25-30 point dozuki, which will soon be found to be a crosscut saw. It will work, because you're only going about 3/4" to the scribe line, but is slow and unconvincing in the cut. It is a good saw for tenon shoulders.
If you do decide you want to commit to Japanese saws, then there are many more good options, but they will be more expensive.
Wiley