My wife (who is a Thai national) and I intend to move to Thailand for at least one year (from Australia). we have a small child and would like to be around my wife's family. I have a BSc (Hons) and I have 5 years + experience in publishing (editing, design etc). I'm 47 yo.

Ideally I would like to get work in the publishing field, possibly with someone who requires someone with good English skills to work on scientific text. That is rather specific but I suspect that there may be some demands for a person with my skill. However, this may be something that a skilled Thai national could also do. My other option would most likely to be teaching English.

Is it possible for me to get some sort of work Visa prior to finding work - a way of making life easier for an employer? Would publishing/editing be considered something that a foreigner could do or maybe I should just stick with the teaching English idea?

Initially I expect that we would stay in Thailand for one year but if things looked good we would probably hope to stay longer.

You need the job to obtain a work permit so that must wait. What you should get now is a non immigrant O visa based on your marriage and it would be good to obtain the multi entry type just in case you do not find work. These are more easily obtained at honorary Consulates.

Do not have information on scientific English requirements but suspect it is limited and probably more need for translation than editing (yes it would be useful but often is not done). But I could well be wrong.