Contact Norton Abrasives and ask about aluminium oxide wheels for sharpening carbon and high speed steel tools and who near you sells them. The colours don't matter so don't fret if they recommend a grey type. They will be able to give you the code numbers for the type and grade of wheels you need. Likely a local machining tool supplier will have or be able to get them for you and likely a better price than the hobby woodworking suppliers. If you already know where the local suppliers are you can ask them directly and they can help you pick them too.
You are probably struggling because of the unique 15mm bore. Look at wheels with a standard 32mm bore and a set of reducers then you're more likely to find the wheels you want. Also, check whether the Creusen wheel is 40mm wide at the bore or whether it is narrower so that you don't get caught out with a wheel that is too wide for the spindle.
I just checked the Axminster website and they do the 1 1/4" to 15mm reducers that you would need.