I can get hydroxycobalamin. Is that OK?

Yes that's OK but your body needs to convert hydroxocobalamin into both methylcobalamin and adenosylcobalamin. And that can only successfully take place IF you have adequate Flavin Adenine Dinucleotide and Flavin Mononucleotide. They are necessary to convert inactive hydroxycobalamin into the active forms of B12. But your body likely is not producing enough of the coenzymes yet to do that efficiently. It can take some time to completely fix Flavin Adenine Dinucleotide and Flavin Mononucleotide deficiencies. So you'd likely benefit more from giving your body methylcobalamin, at least for now. That's what I usually suggest. And then hydroxycobalamincould be considered later. 

But if you really want, you can start with hydroxycobalamin. But you'll need to accept that you may not be very good at converting hydroxycobalamin into the active forms of B12 at this point in time. The conversion may be inefficient at this point in time. But over time, as we fix the coenzymes, your body will definitely be better at making the conversion. So you can start with it right away if you want, as long as you're aware of the downsides.