Do you have carbon parts?
I never known one good all round torque wrench due to the small scale of 4Nm for bars and 65Nm for lock rings on cassettes and had to buy 2.
You want one for 0-15Nm and then one for the cranks and and cassette.
Could set you back £65 each and don't forget the calibration will need setting if you use it often which can be up to £30.
Draper, Sealey and even Halfords do some good stuff.
Also check Motorcycle shops/sites for similar Nm ranges.
They all have 3/8 or 1/2 inch drive fittings and hence will fit the allen key ends.
I chose 3/8 and use 1/2 inch adapter as I found it easier to find allen key ends in 3/8 sizes rather than 1/2" but it depends which shops are near you e.g. Halfords have all allen heads on 3/8" drives.