If you're sharing the specific details of the scam (for example re-posting a copy of the posting or e-mail) and expressing your opinion that it's a scam, you're unlikely to encounter problems.
Problems are likely to arise if you post anything that was not in the original communication - for example if you were to search on a name or e-mail address, and post other information (social media user names, photographs, physical addresses - even approximate ones) based on what you found.
It sounds like you've already considered the possibility that the name and e-mail posted might not relate to the person who posted the scam. The idea that you might be committing libel against a third party by claiming they did something they didn't is worth considering further - particularly if you're alleging criminal activity.
If you link details that were not previously linked, you could also be looking at data protection implications even if you are absolutely certain of their veracity - it's worth bearing in mind that scammers are Natural Persons too. If you were to collate details - for example in a website - these implications become significant.
There's also the question of how you distribute information, which might be relevant even if you're just saying "I saw this posting on that website and I think it's a scam" - a lot of spam consists of warnings about potential scams. If you're posting on someone else's website, there may be terms and conditions to consider.
Confirming with a professional lawyer that the specifics of what you're proposing are legal would give you something to cover your back - but your £260 could also get you the answer that what you're thinking is best avoided.